Science.gov

Sample records for active radiation techniques

  1. The regeneration of polluted activated carbon by radiation techniques

    NASA Astrophysics Data System (ADS)

    Minghong, Wu; Borong, Bao; Ruimin, Zhou; Jinliang, Zhu; Longxin, Hu

    1998-10-01

    In this paper, the regeneration of used activated carbon from monosodium glutamate factory was experimented using radiation and acid-alkali chemical cleaning method. Results showed that the activated carbon saturated with pollutants can be wash away easily by flushing with chemical solution prior irradiation. DSC was used to monitor the change of carbon adsorption

  2. Monolithic active pixel radiation detector with shielding techniques

    DOEpatents

    Deptuch, Grzegorz W.

    2016-09-06

    A monolithic active pixel radiation detector including a method of fabricating thereof. The disclosed radiation detector can include a substrate comprising a silicon layer upon which electronics are configured. A plurality of channels can be formed on the silicon layer, wherein the plurality of channels are connected to sources of signals located in a bulk part of the substrate, and wherein the signals flow through electrically conducting vias established in an isolation oxide on the substrate. One or more nested wells can be configured from the substrate, wherein the nested wells assist in collecting charge carriers released in interaction with radiation and wherein the nested wells further separate the electronics from the sensing portion of the detector substrate. The detector can also be configured according to a thick SOA method of fabrication.

  3. Review of radiation hardening techniques for EDFAs in space environment

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Tian, CuiPing; Wang, YingYing; Wang, Pu

    2015-03-01

    The damage mechanism and test technology of space radiation environment to space equipment was classified and the radiation protection demand of active fiber for space application was analyzed. The radiation hardening techniques of Ce doping, hydrogen loading and pre-radiation exposure and thermal annealing for Er:Yb co-doped fiber was surveyed.

  4. Active cleaning technique device

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B.

    1973-01-01

    The objective of this program was to develop a laboratory demonstration model of an active cleaning technique (ACT) device. The principle of this device is based primarily on the technique for removing contaminants from optical surfaces. This active cleaning technique involves exposing contaminated surfaces to a plasma containing atomic oxygen or combinations of other reactive gases. The ACT device laboratory demonstration model incorporates, in addition to plasma cleaning, the means to operate the device as an ion source for sputtering experiments. The overall ACT device includes a plasma generation tube, an ion accelerator, a gas supply system, a RF power supply and a high voltage dc power supply.

  5. Stereology techniques in radiation biology

    NASA Technical Reports Server (NTRS)

    Kubinova, Lucie; Mao, XiaoWen; Janacek, Jiri; Archambeau, John O.; Nelson, G. A. (Principal Investigator)

    2003-01-01

    Clinicians involved in conventional radiation therapy are very concerned about the dose-response relationships of normal tissues. Before proceeding to new clinical protocols, radiation biologists involved with conformal proton therapy believe it is necessary to quantify the dose response and tolerance of the organs and tissues that will be irradiated. An important focus is on the vasculature. This presentation reviews the methodology and format of using confocal microscopy and stereological methods to quantify tissue parameters, cell number, tissue volume and surface area, and vessel length using the microvasculature as a model tissue. Stereological methods and their concepts are illustrated using an ongoing study of the dose response of the microvessels in proton-irradiated hemibrain. Methods for estimating the volume of the brain and the brain cortex, the total number of endothelial cells in cortical microvessels, the length of cortical microvessels, and the total surface area of cortical microvessel walls are presented step by step in a way understandable for readers with little mathematical background. It is shown that stereological techniques, based on a sound theoretical basis, are powerful and reliable and have been used successfully.

  6. Principles and Techniques of Radiation Chemistry.

    ERIC Educational Resources Information Center

    Dorfman, Leon M.

    1981-01-01

    Discusses the physical processes involved in the deposition of energy from ionizing radiation in the absorber system. Identifies principles relevant to these processes which are responsible for ionization and excitation of the components of the absorber system. Briefly describes some experimental techniques in use in radiation chemical studies.…

  7. Small Active Radiation Monitor

    NASA Technical Reports Server (NTRS)

    Badhwar, Gautam D.

    2004-01-01

    A device, named small active radiation monitor, allows on-orbit evaluations during periods of increased radiation, after extravehicular activities, or at predesignated times for crews on such long-duration space missions as on the International Space Station. It also permits direct evaluation of biological doses, a task now performed using a combination of measurements and potentially inaccurate simulations. Indeed the new monitor can measure a full array of radiation levels, from soft x-rays to hard galactic cosmic-ray particles. With refinement, it will benefit commercial (nuclear power-plant workers, airline pilots, medical technicians, physicians/dentists, and others) and military personnel as well as the astronauts for whom thermoluminescent dosimeters are inadequate. Civilian and military personnel have long since graduated from film badges to thermoluminescent dosimeters. Once used, most dosimeters must be returned to a central facility for processing, a step that can take days or even weeks. While this suffices for radiation workers for whom exposure levels are typically very low and of brief duration, it does not work for astronauts. Even in emergencies and using express mail, the results can often be delayed by as much as 24 hours. Electronic dosimeters, which are the size of electronic oral thermometers, and tattlers, small electronic dosimeters that sound an alarm when the dose/dose rate exceeds preset values, are also used but suffer disadvantages similar to those of thermoluminescent dosimeters. None of these devices fully answers the need of rapid monitoring during the space missions. Instead, radiation is monitored by passive detectors, which are read out after the missions. Unfortunately, these detectors measure only the absorbed dose and not the biologically relevant dose equivalent. The new monitor provides a real-time readout, a time history of radiation exposures (both absorbed dose and biologically relevant dose equivalent), and a count of the

  8. Electron Beam Instrumentation Techniques Using Coherent Radiation

    NASA Astrophysics Data System (ADS)

    Wang, D. X.

    1997-05-01

    In recent years, there has been increasing interest in short electron bunches for different applications such as short wavelength FELs, linear colliders, advanced accelerators such as laser or plasma wakefield accelerators, and Compton backscattering X-ray sources. A short bunch length is needed to meet various requirements such as high peak current, low momentum spread, high luminosity, small ratio of bunch length to plasma wavelength, or accurate timing. Meanwhile, much progress has been made on photoinjectors and different magnetic and RF bunching schemes to produce very short bunches. Measurement of those short bunches becomes essential to develop, characterize, and operate such demanding machines. Conventionally, bunch duration of short electron bunches is measured by transverse RF deflecting cavities or streak camera. With such devices it becomes very challenging to measure bunch length down to a few hundred femtoseconds. Many frequency domain techniques have been recently developed, based on a relation between bunch profile and coherent radiation spectrum. These techniques provide excellent performance for short bunches. In this paper, coherent radiation and its applications to bunch length measurement will be discussed. A strategy for bunch length control at Jefferson Lab will be presented, which includes a noninvasive coherent synchrotron radiation (CSR) monitor, a zero-phasing technique used to calibrate the CSR detector, and phase transfer measurement used to correct RF phase drifts.

  9. Exploring actinide materials through synchrotron radiation techniques.

    PubMed

    Shi, Wei-Qun; Yuan, Li-Yong; Wang, Cong-Zhi; Wang, Lin; Mei, Lei; Xiao, Cheng-Liang; Zhang, Li; Li, Zi-Jie; Zhao, Yu-Liang; Chai, Zhi-Fang

    2014-12-10

    Synchrotron radiation (SR) based techniques have been utilized with increasing frequency in the past decade to explore the brilliant and challenging sciences of actinide-based materials. This trend is partially driven by the basic needs for multi-scale actinide speciation and bonding information and also the realistic needs for nuclear energy research. In this review, recent research progresses on actinide related materials by means of various SR techniques were selectively highlighted and summarized, with the emphasis on X-ray absorption spectroscopy, X-ray diffraction and scattering spectroscopy, which are powerful tools to characterize actinide materials. In addition, advanced SR techniques for exploring future advanced nuclear fuel cycles dealing with actinides are illustrated as well. PMID:25169914

  10. Actively driven thermal radiation shield

    DOEpatents

    Madden, Norman W.; Cork, Christopher P.; Becker, John A.; Knapp, David A.

    2002-01-01

    A thermal radiation shield for cooled portable gamma-ray spectrometers. The thermal radiation shield is located intermediate the vacuum enclosure and detector enclosure, is actively driven, and is useful in reducing the heat load to mechanical cooler and additionally extends the lifetime of the mechanical cooler. The thermal shield is electrically-powered and is particularly useful for portable solid-state gamma-ray detectors or spectrometers that dramatically reduces the cooling power requirements. For example, the operating shield at 260K (40K below room temperature) will decrease the thermal radiation load to the detector by 50%, which makes possible portable battery operation for a mechanically cooled Ge spectrometer.

  11. Advancing Techniques of Radiation Therapy for Rectal Cancer.

    PubMed

    Patel, Sagar A; Wo, Jennifer Y; Hong, Theodore S

    2016-07-01

    Since the advent of radiation therapy for rectal cancer, there has been continual investigation of advancing technologies and techniques that allow for improved dose conformality to target structures while limiting irradiation of surrounding normal tissue. For locally advanced disease, intensity modulated and proton beam radiation therapy both provide more highly conformal treatment volumes that reduce dose to organs at risk, though the clinical benefit in terms of toxicity reduction is unclear. For early stage disease, endorectal contact therapy and high-dose rate brachytherapy may be a definitive treatment option for patients who are poor operative candidates or those with low-lying tumors that desire sphincter-preservation. Finally, there has been growing evidence that supports stereotactic body radiotherapy as a safe and effective salvage treatment for the minority of patients that locally recur following trimodality therapy for locally advanced disease. This review addresses these topics that remain areas of active clinical investigation. PMID:27238474

  12. Kinetic activation-relaxation technique.

    PubMed

    Béland, Laurent Karim; Brommer, Peter; El-Mellouhi, Fedwa; Joly, Jean-François; Mousseau, Normand

    2011-10-01

    We present a detailed description of the kinetic activation-relaxation technique (k-ART), an off-lattice, self-learning kinetic Monte Carlo (KMC) algorithm with on-the-fly event search. Combining a topological classification for local environments and event generation with ART nouveau, an efficient unbiased sampling method for finding transition states, k-ART can be applied to complex materials with atoms in off-lattice positions or with elastic deformations that cannot be handled with standard KMC approaches. In addition to presenting the various elements of the algorithm, we demonstrate the general character of k-ART by applying the algorithm to three challenging systems: self-defect annihilation in c-Si (crystalline silicon), self-interstitial diffusion in Fe, and structural relaxation in a-Si (amorphous silicon). PMID:22181304

  13. Some Radiation Techniques Used in the GU-3 Gamma Irradiator

    SciTech Connect

    Dodbiba, Andon; Ylli, Ariana; Stamo, Iliriana; Kongjika, Efigjeni

    2007-04-23

    Different radiation techniques, measurement of dose and its distibution throughout the irradiated materials are the main problems treated in this paper. The oscillometry method combined with the ionization chamber, as an absolute dosimeter, is used for calibration of routine ECB dosimeters. The dose uniformity, for the used radiation techniques in our GU-3 Gamma Irradiator with Cs-137, is from 93% up to 99%.

  14. New radiosonde techniques to measure radiation profiles through the atmosphere

    NASA Astrophysics Data System (ADS)

    Kräuchi, Andreas; Philipona, Rolf; Romanens, Gonzague; Levrat, Gilbert

    2013-04-01

    Solar and thermal radiation fluxes are usually measured at Earth's surface and at the top of the atmosphere. Here we show radiosonde techniques that allow measuring radiation flux profiles and the radiation budget from the Earth's surface to above 30 km in the stratosphere. During two-hour flights solar shortwave and thermal longwave irradiance, downward and upward, is measured with four individual sensors at one-second resolution, along with standard PTU radiosonde profiles. Daytime and nighttime shortwave and longwave radiation measurements, and 24 hours surface measurements, allow determining radiation budget- and total net radiation profiles through the atmosphere. We use a double balloon technique to prevent pendulum motion during the ascent and to keep the sonde as horizontal as possible. New techniques using auto controlled airplanes are now investigated to retrieve the sonde after release at a certain altitude and to land it if possible at the launch station.

  15. Technique for Radiometer and Antenna Array Calibration with a Radiated Noise Diode

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2009-01-01

    This paper presents a new technique to calibrate a microwave radiometer and antenna array system. This calibration technique uses a radiated noise source in addition to two calibration sources internal to the radiometer. The method accurately calibrates antenna arrays with embedded active devices (such as amplifiers) which are used extensively in active phased array antennas.

  16. Microcurrent therapeutic technique for treatment of radiation toxicity

    DOEpatents

    Lennox, Arlene; Funder, Sandra

    2000-01-01

    The present technique provides a method of remediating the toxicities associated with radiation therapy. A conductive gel is applied to the affected bodily area. A sinusoidally pulsed biphasic DC current is then applied to the affected bodily area using at least one electrode. The electrode is manipulated using active tactile manipulation by for a predetermined time and the frequency of the sinusoidally pulsed biphasic DC current is decreased during the course of the treatment. The method also includes applying a spiked pulsed biphasic DC current to the affected bodily area using at least one electrode. This electrode is also manipulated using active tactile manipulation by for a predetermined time and the frequency of the spiked pulsed biphasic DC current is also decreased during the course of the treatment.

  17. Hybrid hydrogels produced by ionizing radiation technique

    NASA Astrophysics Data System (ADS)

    Oliveira, M. J. A.; Amato, V. S.; Lugão, A. B.; Parra, D. F.

    2012-09-01

    The interest in biocompatible hydrogels with particular properties has increased considerably in recent years due to their versatile applications in biomedicine, biotechnology, pharmacy, agriculture and controlled release of drugs. The use of hydrogels matrices for particular drug-release applications has been investigated with the synthesis of modified polymeric hydrogel of PVAl and 0.5, 1.0, 1.5% nano-clay. They were processed using gamma radiation from Cobalt-60 source at 25 kGy dose. The characterization of the hydrogels was conducted and toxicity was evaluated. The dried hydrogel was analyzed for thermogravimetry analysis (TGA), infrared spectroscopy (FTIR) and swelling in solutions of different pH. The membranes have no toxicity. The nano-clay influences directly the equilibrium swelling.

  18. High accuracy radiation efficiency measurement techniques

    NASA Technical Reports Server (NTRS)

    Kozakoff, D. J.; Schuchardt, J. M.

    1981-01-01

    The relatively large antenna subarrays (tens of meters) to be used in the Solar Power Satellite, and the desire to accurately quantify antenna performance, dictate the requirement for specialized measurement techniques. The error contributors associated with both far-field and near-field antenna measurement concepts were quantified. As a result, instrumentation configurations with measurement accuracy potential were identified. In every case, advances in the state of the art of associated electronics were found to be required. Relative cost trade-offs between a candidate far-field elevated antenna range and near-field facility were also performed.

  19. Flow-cytometry techniques in radiation biology

    SciTech Connect

    McCarthy, K.F.; Hale, M.L.

    1988-01-01

    Considerable evidence exists that all blood cells are derived from HSC. These cells are of interest to radiobiologists because they are highly sensitive to low doses of ionizing radiation. Hematopoietic stem cells (HSC) are present in the marrow at a concentration of approximately 2-3 HSC per 1000 nucleated marrow cells. In the past, only clonogenic assays requiring 8-13 days and ten irradiated recipient rodents were available for assaying HSC. Because of the importance of HSC in the post-irradiation syndrome, the authors developed a new rapid method based on flow cytometry not only to assay but also to purify and characterize HSC. This new method makes extensive use of non-clonal antibodies conjugated to fluorescent phycobiliproteins through the sulfhydryls of the hinge region of the IgG molecule. An optical bench arrangement with a dye laser and an argon laser was used for dual excitation of the phycobiliprotein-monoclonal antibody conjugates and various cellular and DNA probes. Using 4', 6-diamidino 2-phenylindole dihydrochloride (DAP) exclusion to identify viable cells, it was possible to follow regeneration of post-irradiated rat marrow HSC.

  20. Development of "active correlation" technique

    NASA Astrophysics Data System (ADS)

    Tsyganov, Yu. S.

    2016-01-01

    With reaching to extremely high intensities of heavy-ion beams new requirements for the detection system of the Dubna Gas-Filled Recoil Separator (DGFRS) will definitely be set. One of the challenges is how to apply the "active correlations" method to suppress beam associated background products without significant losses in the whole long-term experiment efficiency value. Different scenarios and equations to develop the method according this requirement are under consideration in the present paper. The execution time to estimate the dead time parameter associated with the optimal choice of the life-time parameter is presented.

  1. Recent progress in the transition radiation detector techniques

    NASA Technical Reports Server (NTRS)

    Yuan, L. C. L.

    1973-01-01

    A list of some of the major experimental achievements involving charged particles in the relativistic region are presented. With the emphasis mainly directed to the X-ray region, certain modes of application of the transition radiation for the identification and separation of relativistic charged particles are discussed. Some recent developments in detection techniques and improvements in detector performances are presented. Experiments were also carried out to detect the dynamic radiation, but no evidence of such an effect was observed.

  2. New techniques of low level environmental radiation monitoring at JLab

    SciTech Connect

    P. Degtiarenko, V. Popov

    2010-07-01

    We present the first long-term environmental radiation monitoring results obtained using the technique of pulse mode readout for the industry-standard Reuter-Stokes RSS-1013 argon-filled high pressure ionization chambers (HPIC). With novel designs for the front-end electronics readout and customized signal processing algorithms, we are capable of detecting individual events of gas ionization in the HPIC, caused by interactions of gammas and charged particles in the gas. The technique provides enough spectroscopic information to distinguish between several different types of environmental and man-made radiation. The technique also achieves a high degree of sensitivity and stability of the data, allowing long-term environmental radiation monitoring with unprecedented precision.

  3. Radiation protection for manned space activities

    NASA Technical Reports Server (NTRS)

    Jordan, T. M.

    1983-01-01

    The Earth's natural radiation environment poses a hazard to manned space activities directly through biological effects and indirectly through effects on materials and electronics. The following standard practices are indicated that address: (1) environment models for all radiation species including uncertainties and temporal variations; (2) upper bound and nominal quality factors for biological radiation effects that include dose, dose rate, critical organ, and linear energy transfer variations; (3) particle transport and shielding methodology including system and man modeling and uncertainty analysis; (4) mission planning that includes active dosimetry, minimizes exposure during extravehicular activities, subjects every mission to a radiation review, and specifies operational procedures for forecasting, recognizing, and dealing with large solar flaes.

  4. Fabrication techniques for reverse electrode coaxial germanium nuclear radiation detectors

    SciTech Connect

    Hansen, W.L.; Haller, E.E.

    1980-11-01

    Germanium detectors with reverse polarity coaxial electrodes have been shown to exhibit improved resistance to radiation damage as compared with conventional electrode devices. However, the production of reverse electrode devices involves the development of new handling and fabrication techniques which has limited their wider application. We have developed novel techniques which lead to a device which is simple to fabricate, environmentally passivated and surface state adjusted.

  5. RADIOFREQUENCY RADIATION: ACTIVITIES AND ISSUES

    EPA Science Inventory

    The question of human safety relative to exposure to RF radiation obviously predates the first ANSI guideline established in 1966, but no enforceable Federal standards or guidelines exist for RF radiation exposure; the ANSI guideline which was revised in 1982 is voluntary or advi...

  6. The radiation techniques of tomotherapy & intensity-modulated radiation therapy applied to lung cancer

    PubMed Central

    Zhu, Zhengfei

    2015-01-01

    Radiotherapy (RT) plays an important role in the management of lung cancer. Development of radiation techniques is a possible way to improve the effect of RT by reducing toxicities through better sparing the surrounding normal tissues. This article will review the application of two forms of intensity-modulated radiation therapy (IMRT), fixed-field IMRT and helical tomotherapy (HT) in lung cancer, including dosimetric and clinical studies. The advantages and potential disadvantages of these two techniques are also discussed. PMID:26207214

  7. Measurement of radiation exposure of astronauts by radiochemical techniques

    NASA Technical Reports Server (NTRS)

    Brodzinski, R. L.

    1973-01-01

    A cosmic radiation dose to the Apollo 16 crew of 180 + or - 100 mR was calculated from the specific activities of Na-22 and Na-24 in pre and postflight urine specimens. The specific activities of Cr-51 and Co-60 are higher in postflight specimens than in preflight specimens, presumably due to a postflight injection of radiochromium. The Fe-59 and Cs-137 specific activities are also reported and appear to be normal. The radiation doses received by a pilot and a navigator flying a high altitude mission during the solar flare of August 4 to 9, 1972 were calculated from the specific activity of Na-24 in their urine. These values are compared with the expected radiation dose calculated form the known shape and intensity of the proton spectrum. They demonstrate the magnitude of atmospheric shielding.

  8. Radiation Effects and Hardening Techniques for Spacecraft Microelectronics

    NASA Astrophysics Data System (ADS)

    Gambles, J. W.; Maki, G. K.

    2002-01-01

    The natural radiation from the Van Allen belts, solar flares, and cosmic rays found outside of the protection of the earth's atmosphere can produce deleterious effects on microelectronics used in space systems. Historically civil space agencies and the commercial satellite industry have been able to utilize components produced in special radiation hardened fabrication process foundries that were developed during the 1970s and 1980s under sponsorship of the Departments of Defense (DoD) and Energy (DoE). In the post--cold war world the DoD and DoE push to advance the rad--hard processes has waned. Today the available rad--hard components lag two-plus technology node generations behind state- of-the-art commercial technologies. As a result space craft designers face a large performance gap when trying to utilize available rad--hard components. Compounding the performance gap problems, rad--hard components are becoming increasingly harder to get. Faced with the economic pitfalls associated with low demand versus the ever increasing investment required for integrated circuit manufacturing equipment most sources of rad--hard parts have simply exited this market in recent years, leaving only two domestic US suppliers of digital rad--hard components. This paper summarizes the radiation induced mechanisms that can cause digital microelectronics to fail in space, techniques that can be applied to mitigate these failure mechanisms, and ground based testing used to validate radiation hardness/tolerance. The radiation hardening techniques can be broken down into two classes, Hardness By Process (HBP) and Hardness By Design (HBD). Fortunately many HBD techniques can be applied to commercial fabrication processes providing space craft designer with radiation tolerant Application Specific Integrated Circuits (ASICs) that can bridge the performance gap between the special HBP foundries and the commercial state-of-the-art performance.

  9. Active galaxies and radiative heating.

    PubMed

    Ostriker, Jeremiah P; Ciotti, Luca

    2005-03-15

    There is abundant evidence that heating processes in the central regions of elliptical galaxies have both prevented large-scale cooling flows and assisted in the expulsion of metal rich gas. We now know that each such spheroidal system harbours in its core a massive black hole weighing ca. 0.13% of the mass in stars and also know that energy was emitted by each of these black holes with an efficiency exceeding 10% of its rest mass. Since, if only 0.5% of that radiant energy were intercepted by the ambient gas, its thermal state would be drastically altered, it is worth examining in detail the interaction between the out-flowing radiation and the equilibrium or inflowing gas. On the basis of detailed hydrodynamic computations we find that relaxation oscillations are to be expected with the radiative feedback quite capable of regulating both the growth of the central black hole and also the density and thermal state of the gas in the galaxy. Mechanical input of energy by jets may assist or dominate over these radiative effects. We propose specific observational tests to identify systems which have experienced strong bursts of radiative heating from their central black holes. PMID:15681285

  10. Numerical Techniques for Coupled Ring Current - Radiation Belt Modelling

    NASA Astrophysics Data System (ADS)

    Aseev, N.; Shprits, Y.

    2015-12-01

    The dynamics of electrons in the Earth's radiation belts can be described by the Fokker-Planck equation which includes radial diffusion and local energy and pitch angle diffusion. Versatile Electron Radiation Belt (VERB-3D) code was developed to solve the Fokker-Planck equation. It incorporates a range of numerical techniques which are appropriate for this purpose. The code has been recently extended to include convection and now solves the convection-diffusion problem in 4D. The report is devoted to several numerical algorithms for modeling of the Earth's radiation belts. We concentrate on high-order schemes ( 7th and 9th order) for solution of an advection-diffusion problem in 1D, 2D,3D and 4D. Results of tests performed to study accuracy and speed of these schemes are presented in the report.

  11. Technique to Predict Ultraviolet Radiation Embrittlement of Polymers in Space

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In the low-Earth-orbit environment, solar ultraviolet (UV) radiation embrittles polymer materials through bond breaking and crosslinking. This UV embrittlement increases the surface hardness of the polymer. Before the durability of polymer materials in the low- Earth-orbit environment can be predicted, the extent of UV embrittlement needs to be determined. However, traditional techniques for measuring the microhardness of materials cannot be employed to measure changes in the hardness of UV-embrittled surfaces because traditional techniques measure bulk hardness and are not sensitive enough to surface changes. A unique technique was used at the NASA Lewis Research Center to quantify polymer surface damage that had been induced by UV radiation. The technique uses an atomic force microscope (AFM) to measure surface microhardness. An atomic force microscope measures the repulsive forces between the atoms in a microscopic cantilevered tip and the atoms on the surface of a sample. Typically, an atomic force microscope produces a topographic image of a surface by monitoring the movement of the tip over features of the surface. The force applied to the cantilevered tip, and the indention of the tip into the surface, can be measured. The relationship between force and distance of indentation, the quantity force/distance (newtons/meter), provides a measure of the surface hardness. Under identical operating conditions, direct comparisons of surface hardness values can be made.

  12. Review of measurement techniques for the neutron radiative-capture process

    SciTech Connect

    Poenitz, W.P.

    1981-07-01

    The experimental techniques applied in measurements of the neutron capture process are reviewed. The emphasis is on measurement techniques used in neutron capture cross section measurements. The activation technique applied mainly in earlier work has still its use in some cases, specifically for measurements of technologically important cross sections (/sup 238/U and /sup 232/Th) with high accuracy. Three major prompt neutron radioactive capture detection techniques have evolved: the total gamma radiation energy detection technique (mainly with large liquid scintillation detectors), the gamma-energy proportional detectors (with proportional counters or Moxon-Rae detectors), and the pulse-height weighting technique. These measurement techniques are generally applicable, however, shortcomings limit the achievable accuracy to a approx. = 5 to 15% uncertainty level.

  13. The measurement of radiation exposure of astronauts by radiochemical techniques

    NASA Technical Reports Server (NTRS)

    Brodzinski, R. L.

    1972-01-01

    Cosmic radiation doses to the crews of the Apollo 14, 15, and 16 missions of 142 + or - 80, 340 + or - 80, and 210 + or - 130 mR respectively were calculated from the specific activities of Na-22 and Na-24 in the postflight urine specimens of the astronauts. The specific activity of Fe-59 was higher in the urine than in the feces of the Apollo 14 and 15 astronauts, and a possible explanation is given. The concentrations of K-40, K-42, Cr-51, Co-60, and Cs-137 in the urine are also reported for these astronauts. The radiation doses received by pilots and navigators flying high altitude missions during the solar flare of March 27 to 30, 1972 were calculated from the specific activity of Na-24 in their urine. These values are compared with the expected radiation dose calculated from the known shape and intensity of the proton spectrum and demonstrate the magnitude of atmospheric shielding. The concentrations of Na, K, Rb, Cs, Fe, Co, Ag, Zn, Hg, As, Sb, Se, and Br were measured in the urine specimens from the Apollo 14 and 15 astronauts by neutron activation analysis. The mercury and arsenic levels were much higher than expected.

  14. Active personal radiation monitor for lunar EVA

    NASA Astrophysics Data System (ADS)

    Straume, Tore; Borak, Tom; Braby, L. A.; Lusby, Terry; Semones, Edward J.; Vazquez, Marcelo E.

    As astronauts return to the Moon-and this time, work for extended periods-there will be a critical need for crew personnel radiation monitoring as they operate lunar rovers or otherwise perform a myriad of extravehicular activities (EVAs). Our focus is on development of a small personal radiation monitor for lunar EVA that responds to the complex radiation quality and changing dose rates on the Moon. Of particular concern are active monitoring capabilities that provide both early warning and radiation dosimetry information during solar particle events (SPEs). To accomplish this, we are developing small detectors integrated with modern high speed, low power microelectronics to measure dose-rate and dose-mean lineal energy in real time. The monitor is designed to perform over the range of dose rates and LETs expected from both GCR and SPE radiations during lunar EVA missions. The monitor design provides simultaneous measurement of dose-equivalent rates at two tissue-equivalent depths simulating skin and marrow. The compact personal monitor is estimated to be the size of a cell phone and would fit on an EVA spacesuit (e.g., in backpack) or in a toolbox. The four-year development effort (which began December 2007) will result in a prototype radiation monitor field tested and characterized for the major radiations expected on the surface of the Moon. We acknowledge support from NSBRI through grants to NASA Ames Research Center (T. Straume, PI) and Colorado State University (T. Borak, PI).

  15. Eigenspace techniques for active flutter suppression

    NASA Technical Reports Server (NTRS)

    Garrard, William L.; Liebst, Bradley S.; Farm, Jerome A.

    1987-01-01

    The use of eigenspace techniques for the design of an active flutter suppression system for a hypothetical research drone is discussed. One leading edge and two trailing edge aerodynamic control surfaces and four sensors (accelerometers) are available for each wing. Full state control laws are designed by selecting feedback gains which place closed loop eigenvalues and shape closed loop eigenvectors so as to stabilize wing flutter and reduce gust loads at the wing root while yielding accepatable robustness and satisfying constrains on rms control surface activity. These controllers are realized by state estimators designed using an eigenvalue placement/eigenvector shaping technique which results in recovery of the full state loop transfer characteristics. The resulting feedback compensators are shown to perform almost as well as the full state designs. They also exhibit acceptable performance in situations in which the failure of an actuator is simulated.

  16. Active load control techniques for wind turbines.

    SciTech Connect

    van Dam, C.P.; Berg, Dale E.; Johnson, Scott J.

    2008-07-01

    This report provides an overview on the current state of wind turbine control and introduces a number of active techniques that could be potentially used for control of wind turbine blades. The focus is on research regarding active flow control (AFC) as it applies to wind turbine performance and loads. The techniques and concepts described here are often described as 'smart structures' or 'smart rotor control'. This field is rapidly growing and there are numerous concepts currently being investigated around the world; some concepts already are focused on the wind energy industry and others are intended for use in other fields, but have the potential for wind turbine control. An AFC system can be broken into three categories: controls and sensors, actuators and devices, and the flow phenomena. This report focuses on the research involved with the actuators and devices and the generated flow phenomena caused by each device.

  17. Image Guidance in Radiation Therapy: Techniques and Applications

    PubMed Central

    Kataria, Tejinder

    2014-01-01

    In modern day radiotherapy, the emphasis on reduction on volume exposed to high radiotherapy doses, improving treatment precision as well as reducing radiation-related normal tissue toxicity has increased, and thus there is greater importance given to accurate position verification and correction before delivering radiotherapy. At present, several techniques that accomplish these goals impeccably have been developed, though all of them have their limitations. There is no single method available that eliminates treatment-related uncertainties without considerably adding to the cost. However, delivering “high precision radiotherapy” without periodic image guidance would do more harm than treating large volumes to compensate for setup errors. In the present review, we discuss the concept of image guidance in radiotherapy, the current techniques available, and their expected benefits and pitfalls. PMID:25587445

  18. Implementation of Image-Guidance Techniques in Radiation Therapy

    NASA Astrophysics Data System (ADS)

    Thomas, Michael; Clark, Brenda; MacPherson, Miller; Montgomery, Lynn; Gerig, Lee

    2008-06-01

    For more than 100 years, physicists have been a vital part of the medical team required to deliver radiation therapy. Their role encompasses the verification of dose accuracy to the development and implementation of new techniques, the most recent of which is the incorporation of daily image guidance to account for inter- and intra-fraction target changes. For example, computed tomography (CT) integrated into radiotherapy treatment units allows the image-guided treatment of the prostate where the target location depends on the degree of rectal filling--a parameter that changes on timescales from minutes to weeks. Different technology is required for the adequate treatment of small lung tumours since respiration occurs on timescales of seconds. This presentation will review current image-guided techniques.

  19. Studying photonuclear reactions using the activation technique

    NASA Astrophysics Data System (ADS)

    Belyshev, S. S.; Ermakov, A. N.; Ishkhanov, B. S.; Khankin, V. V.; Kurilik, A. S.; Kuznetsov, A. A.; Shvedunov, V. I.; Stopani, K. A.

    2014-05-01

    The experimental setup that is used at the Skobeltsyn Institute of Nuclear Physics of the Moscow State University to study photonuclear reactions using the activation technique is described. The system is based on two modern compact race track microtrons with maximum energy of electrons of up to 55 and 67.7 MeV. A low-background HPGe detector is used to measure the induced gamma activity. The data acquisition and analysis system, used to process the measured spectra, is described. The described system is used to study multiparticle photonuclear reactions and production of nuclei far from the beta stability region.

  20. High pressure x-ray diffraction techniques with synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Jing, Liu

    2016-07-01

    This article summarizes the developments of experimental techniques for high pressure x-ray diffraction (XRD) in diamond anvil cells (DACs) using synchrotron radiation. Basic principles and experimental methods for various diffraction geometry are described, including powder diffraction, single crystal diffraction, radial diffraction, as well as coupling with laser heating system. Resolution in d-spacing of different diffraction modes is discussed. More recent progress, such as extended application of single crystal diffraction for measurements of multigrain and electron density distribution, time-resolved diffraction with dynamic DAC and development of modulated heating techniques are briefly introduced. The current status of the high pressure beamline at BSRF (Beijing Synchrotron Radiation Facility) and some results are also presented. Project supported by the National Natural Science Foundation of China (Grant Nos. 10875142, 11079040, and 11075175). The 4W2 beamline of BSRF was supported by the Chinese Academy of Sciences (Grant Nos. KJCX2-SW-N20, KJCX2-SW-N03, and SYGNS04).

  1. Radiation and photografting as complementary techniques for immobilizing bioactive materials

    NASA Astrophysics Data System (ADS)

    Garnett, J. L.; Jankiewicz, S. V.; Long, M. A.; Sangster, D. F.

    The technique of radiation grafting to immobilize a typical enzyme, trypsin, to three representative backbone polymers namely polypropylene, PVC and polystyrene, is described. The process involves the simultaneous grafting of p-nitrostyrene to the polymer, the nitro group subsequently being converted to its isothiocyanato derivative to which trypsin is attached. For this immobilization work, the utilization of additives which enhance grafting is shown to be an advantage. Typical of the additives used are mineral acids (≈0.1M) and polyfunctional monomers (≈1% v/v), the two acting in a synergistic fashion when used together. A new class of additives, namely metal salts such as LiClO 4, which also increase grafting yields has now been discovered. The reactivity of these salts in grafting enhancement is compared with that of mineral acid. A new model for the modus operandi of metal salts as well as acids in grafting enhancement is proposed whereby increased grafting yields are attributed to increased partitioning of monomer into the graft region in the presence of ionic solutes. The significance of using these additives to prepare radiation copolymers for enzyme immobilization is discussed. In addition to ionizing radiation, UV is also shown to be of value as an initiator for the preparation of graft copolymers for enzyme immobilization, however the presence of sensitizer in the copolymer may limit the photografting method. The possibility of using radiation curing processes involving electron beam (EB) and high powered (300 W/inch) UV sources for immobilization work has been explored and found to be feasible. The curing system possesses great potential for the current immobilization work since complete polymerization is achieved in a fraction of a second.

  2. Measurement of radiation exposure of astronauts by radiochemical techniques

    NASA Technical Reports Server (NTRS)

    Brodzinski, R. L.

    1973-01-01

    A cosmic radiation dose to the Apollo 17 crew of 1.3 R was calculated from the specific activities of Na-24 in their postflight urine specimens. The specific activities of K-42, Cr-51, Co60, and Sb-124, introduced by injection into the astronauts, are extremely high in these specimens. The Fe-59 and Cs-137 levels are also reported and appear to be normal. The concentrations of Na, K, Rb, Cs, Ca, Sr, Ba, Cr, Fe, Co, Ag, Au, Zn, Cd, Hg, Sn, As, Sb, Se, Br, Sc, La, Sm, Eu, Tb, Hf, Ta, and Th were measured in urine specimens from the Apollo 17 astronauts by neutron activation analysis. Strontium, barium, gold, cadmium, lanthanum, samarium, europium, terbium, thorium, and tin are reported for the first time. The concentrations or excretion rates of bromine and the alkali metals exhibit singificantly reduced postflight levels and are generally lower than values observed for previous missions. Chromium concentrations reflect radiochromium injections.

  3. Control of sound radiation with active/adaptive structures

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.; Rogers, C. A.; Robertshaw, H. H.

    1992-01-01

    Recent research is discussed in the area of active structural acoustic control with active/adaptive structures. Progress in the areas of structural acoustics, actuators, sensors, and control approaches is presented. Considerable effort has been given to the interaction of these areas with each other due to the coupled nature of the problem. A discussion is presented on actuators bonded to or embedded in the structure itself. The actuators discussed are piezoceramic actuators and shape memory alloy actuators. The sensors discussed are optical fiber sensors, Nitinol fiber sensors, piezoceramics, and polyvinylidene fluoride sensors. The active control techniques considered are state feedback control techniques and least mean square adaptive algorithms. Results presented show that significant progress has been made towards controlling structurally radiated noise by active/adaptive means applied directly to the structure.

  4. Radiation synthesized protein-based nanoparticles: A technique overview

    NASA Astrophysics Data System (ADS)

    Varca, Gustavo H. C.; Perossi, Gabriela G.; Grasselli, Mariano; Lugão, Ademar B.

    2014-12-01

    Seeking for alternative routes for protein engineering a novel technique - radiation induced synthesis of protein nanoparticles - to achieve size controlled particles with preserved bioactivity has been recently reported. This work aimed to evaluate different process conditions to optimize and provide an overview of the technique using γ-irradiation. Papain was used as model protease and the samples were irradiated in a gamma cell irradiator in phosphate buffer (pH=7.0) containing ethanol (0-35%). The dose effect was evaluated by exposure to distinct γ-irradiation doses (2.5, 5, 7.5 and 10 kGy) and scale up experiments involving distinct protein concentrations (12.5-50 mg mL-1) were also performed. Characterization involved size monitoring using dynamic light scattering. Bityrosine detection was performed using fluorescence measurements in order to provide experimental evidence of the mechanism involved. Best dose effects were achieved at 10 kGy with regard to size and no relevant changes were observed as a function of papain concentration, highlighting very broad operational concentration range. Bityrosine changes were identified for the samples as a function of the process confirming that such linkages play an important role in the nanoparticle formation.

  5. Laser-heating-based active optics for synchrotron radiation applications.

    PubMed

    Yang, Fugui; Li, Ming; Gao, Lidan; Sheng, Weifan; Liu, Peng; Zhang, Xiaowei

    2016-06-15

    Active optics has attracted considerable interest from researchers in synchrotron radiation facilities because of its capacity for x-ray wavefront correction. Here, we report a novel and efficient technique for correcting or modulating a mirror surface profile based on laser-heating-induced thermal expansion. An experimental study of the characteristics of the surface thermal deformation response indicates that the power of a milliwatt laser yields a bump height as low as the subnanometer scale and that the variation of the spot size modulates the response function width effectively. In addition, the capacity of the laser-heating technique for free-form surface modulation is demonstrated via a one-dimensional surface correction experiment. The developed method is a promising new approach toward effective x-ray active optics coupled with at-wavelength metrology techniques. PMID:27304296

  6. Continuous dosimetry of the biologically harmful UV-radiation in Antarctica with the biofilm technique.

    PubMed

    Quintern, L E; Puskeppeleit, M; Rainer, P; Weber, S; el Naggar, S; Eschweiler, U; Horneck, G

    1994-01-01

    For the first time, a continuous biological dosimetry experiment for cytotoxic solar UV-radiation has been performed in Antarctica. The biologically harmful UV-radiation on the ground was measured at the German Antarctic Georg von Neumayer Station (70 degrees 37' S, 80 degrees 22' W) from December 1990 to March 1992 using the biofilm technique. The UV-sensitive targets were dried spores of Bacillus subtilis which were immobilized on the film surface. The UV-induced inhibition of biological activity, determined photometrically from the protein synthesized after incubation and staining, was taken as a measure for the absorbed UV-dose. Films were exposed in horizontal position for time intervals ranging from 4 days during summer up to 51 and 41 days before and after the polar night respectively. The use of different cut-off filters allowed the calculation of the biologically effective UVA, UVB and the complete UV-radiation (UVA + B). The data were compared with the global radiation and the ozone column thickness indicating an increase of biologically harmful UVB radiation during austral spring at reduced ozone concentrations yielding a radiation amplification factor (RAF) of 1.4, whereas for the total UV(A + B) range the RAF amounted to 0.3. PMID:8151457

  7. Active Correlation Technique: Status and Development

    SciTech Connect

    Tsyganov, Yury

    2010-04-30

    During the recent years, at the FLNR (JINR) a successful cycle of experiments has been accomplished on the synthesis of the superheavy elements with Z = 112-118 with {sup 48}Ca beam. From the viewpoint of the detection of rare decays and background suppression, this success was achieved due to the application of a new radical technique--the method of active correlations. The method employs search in a real-time mode for a pointer to a probable correlation like recoil-alpha for switching the beam off. In the case of detection in the same detector strip an additional alpha-decay event, of 'beam OFF' time interval is prolonged automatically.

  8. Auroral kilometric radiation source characteristics using ray tracing techniques

    NASA Astrophysics Data System (ADS)

    Schreiber, R.; Santolik, O.; Parrot, M.; Lefeuvre, F.; Hanasz, J.; Brittnacher, M.; Parks, G.

    2002-11-01

    3-D ray tracing to the presumed auroral kilometric radiation (AKR) source region has been performed using the input data from wave distribution function (WDF) based on the AKR waveforms recorded on board the Interball 2 satellite by the French wave experiment MEMO. Both the direction of the WDF maximum and the WDF form and angular size have been taken into account. Two instances of AKR emissions were observed on 28 January 1997 at 2037 and 2107 UT. Rays traced in R-X mode out of the s/c point toward two different active regions on the auroral oval (as seen with Polar UV imager after projection of the source region along the magnetic field lines down to the ionosphere level). Source region apparent angular sizes based on WDF are compatible with sizes estimated from signal modulation produced by electric antenna system rotation.

  9. Radiation treatment planning techniques for lymphoma of the stomach

    SciTech Connect

    Della Biancia, Cesar; Hunt, Margie; Furhang, Eli; Wu, Elisa; Yahalom, Joachim . E-mail: yahalomj@mskcc.org

    2005-07-01

    Purpose: Involved-field radiation therapy of the stomach is often used in the curative treatment of gastric lymphoma. Yet, the optimal technique to irradiate the stomach with minimal morbidity has not been well established. This study was designed to evaluate treatment planning alternatives for stomach irradiation, including intensity-modulated radiation therapy (IMRT), to determine which approach resulted in improved dose distribution and to identify patient-specific anatomic factors that might influence a treatment planning choice. Methods and Materials: Fifteen patients with lymphoma of the stomach (14 mucosa-associated lymphoid tissue lymphomas and 1 diffuse large B-cell lymphoma) were categorized into 3 types, depending on the geometric relationship between the planning target volume (PTV) and kidneys. AP/PA and 3D conformal radiation therapy (3DCRT) plans were generated for each patient. IMRT was planned for 4 patients with challenging geometric relationship between the PTV and the kidneys to determine whether it was advantageous to use IMRT. Results: For type I patients (no overlap between PTV and kidneys), there was essentially no benefit from using 3DCRT over AP/PA. However, for patients with PTVs in close proximity to the kidneys (type II) or with high degree of overlap (type III), the 4-field 3DCRT plans were superior, reducing the kidney V {sub 15Gy} by approximately 90% for type II and 50% for type III patients. For type III, the use of a 3DCRT plan rather than an AP/PA plan decreased the V {sub 15Gy} by approximately 65% for the right kidney and 45% for the left kidney. In the selected cases, IMRT led to a further decrease in left kidney dose as well as in mean liver dose. Conclusions: The geometric relationship between the target and kidneys has a significant impact on the selection of the optimum beam arrangement. Using 4-field 3DCRT markedly decreases the kidney dose. The addition of IMRT led to further incremental improvements in the left kidney

  10. Radiation Detection for Active Interrogation of HEU

    SciTech Connect

    Mihalczo, J.T.

    2004-12-09

    This report briefly describes the neutrons and gamma rays emitted by active interrogation of HEU, briefly discusses measurement methods, briefly discusses sources and detectors relevant to detection of shielded HEU in Sealand containers, and lists the measurement possibilities for the various sources. All but one of the measurement methods detect radiation emitted by induced fission in the HEU; the exception utilizes nuclear resonance fluorescence. The brief descriptions are supplemented by references. This report presents some active interrogation possibilities but the status of understanding is not advanced enough to select particular methods. Additional research is needed to evaluate these possibilities.

  11. Impact of advanced microstructural characterization techniques on modeling and analysis of radiation damage

    SciTech Connect

    Garner, F.A.; Odette, G.R.

    1980-01-01

    The evolution of radiation-induced alterations of dimensional and mechanical properties has been shown to be a direct and often predictable consequence of radiation-induced microstructural changes. Recent advances in understanding of the nature and role of each microstructural component in determining the property of interest has led to a reappraisal of the type and priority of data needed for further model development. This paper presents an overview of the types of modeling and analysis activities in progress, the insights that prompted these activities, and specific examples of successful and ongoing efforts. A review is presented of some problem areas that in the authors' opinion are not yet receiving sufficient attention and which may benefit from the application of advanced techniques of microstructural characterization. Guidelines based on experience gained in previous studies are also provided for acquisition of data in a form most applicable to modeling needs.

  12. Radiations and biodegradation techniques for detoxifying Carica papaya seed oil for effective dietary and industrial use.

    PubMed

    Afolabi, Israel Sunmola; Bisi-Adeniyi, Tolulope Dorcas; Adedoyin, Toluwalase Ronke; Rotimi, Solomon Oladapo

    2015-10-01

    Benzyl isothiocyanate (BITC) is toxic in high concentration. The capacity of Aspergillus niger, microwave and ultraviolet radiations to reduce the BITC levels in Carica papaya Linn seed oil were assessed in vitro. BITC at different concentrations were periodically exposed to microwave and ultraviolet radiations for 30 min and 10 h, respectively; and to identify Aspergillus niger for 4 days. Microwave radiation significantly reduced (p < 0.05) BITC levels (0.0272, 0.0544, and 0.0816 μmol) to 12.19, 8.99 and 27.5 % respectively within 15 min. Ultraviolet radiation significantly reduced (p < 0.05) BITC levels at all the concentrations. A. niger significantly increased (p < 0.05) BITC degradation on days 2 and 4 at 0.816, 1.36 and 2.72 nmol. Glutathione activity was significantly increased (p < 0.05) while glutathione S-transferase activity significantly reduced (p < 0.05) at all concentrations on days 3 and 4 respectively. The three techniques are possible models for improving the dietary consumption of the oil. PMID:26396392

  13. Measurement of radiation exposure of astronauts by radiochemical techniques

    NASA Technical Reports Server (NTRS)

    Brodzinski, R. L.

    1972-01-01

    Only two of the fecal specimens collected inflight during the Apollo 15 mission were returned for analysis. Difficulty in obtaining reasonably accurate radiation dose estimates based on the cosmogenic radionuclide content of the specimens was encountered due to the limited sampling. The concentrations of Na-22, K-40, Cr-51, Fe-59, and Cs-137 are reported. The concentrations of 24 major, minor, and trace elements in these two specimens were determined. Most concentrations are typical of those observed previously. Major exceptions are extremely low values for selenium and extraordinarily high values for rare earth elements. The net Po-210 activities in the Apollo 11 and 12 Solar Wind Composition foils and in the Apollo 8 and 12 spacecraft reflective coatings due to lunar exposure have been determined. Equilibrium concentrations of 0.082 + or - 0.012 disintegrations /sq cm sec of Rn-222 in the lunar atmosphere and 0.0238 + or - 0.0035 disintegrations /sq cm sec of Po-210 on the lunar surface have been calculated for Oceanus Procellarum.

  14. Photocatalytic Active Radiation Measurements and Use

    NASA Technical Reports Server (NTRS)

    Davis, Bruce A.; Underwood, Lauren W.

    2011-01-01

    Photocatalytic materials are being used to purify air, to kill microbes, and to keep surfaces clean. A wide variety of materials are being developed, many of which have different abilities to absorb various wavelengths of light. Material variability, combined with both spectral illumination intensity and spectral distribution variability, will produce a wide range of performance results. The proposed technology estimates photocatalytic active radiation (PcAR), a unit of radiation that normalizes the amount of light based on its spectral distribution and on the ability of the material to absorb that radiation. Photocatalytic reactions depend upon the number of electron-hole pairs generated at the photocatalytic surface. The number of electron-hole pairs produced depends on the number of photons per unit area per second striking the surface that can be absorbed and whose energy exceeds the bandgap of the photocatalytic material. A convenient parameter to describe the number of useful photons is the number of moles of photons striking the surface per unit area per second. The unit of micro-einsteins (or micromoles) of photons per m2 per sec is commonly used for photochemical and photoelectric-like phenomena. This type of parameter is used in photochemistry, such as in the conversion of light energy for photosynthesis. Photosynthetic response correlates with the number of photons rather than by energy because, in this photochemical process, each molecule is activated by the absorption of one photon. In photosynthesis, the number of photons absorbed in the 400 700 nm spectral range is estimated and is referred to as photosynthetic active radiation (PAR). PAR is defined in terms of the photosynthetic photon flux density measured in micro-einsteins of photons per m2 per sec. PcAR is an equivalent, similarly modeled parameter that has been defined for the photocatalytic processes. Two methods to measure the PcAR level are being proposed. In the first method, a calibrated

  15. Review of active radiation shielding developments

    NASA Astrophysics Data System (ADS)

    Battiston, Roberto

    The radiation risk due to ionizing particles is a critical issue for long duration manned space missions. The ionization losses in the materials of the spacecraft provide passive shielding effectively stopping low energy particles. However, the estimates of the material required to obtain an acceptable level of radiation result in a prohibitive mass. Active electromagnetic shields, which deflect the charged particles, have been considered as an alternative solution. During the last 10 years the interest in this area has grown. A study of active magnetic shielding based on high-temperature superconductors (HTS) was initiated in an ESA study in 2010, continued in the context of the NASA Innovative Advanced Concepts (NIAC) programs (2011-2014) as well as within a dedicated FP7 EU program, SR2S (2013-2015). The aim of these effort was to provide a realistic evaluation of the possibilities based on current technology levels as well extrapolating to reasonable technology advances expected during the next decade. The different configurations considered were assessed in terms of their technical feasibility and shielding efficiency. We present here a status report of the ongoing work and some preliminary results.

  16. Neutron Activation Analysis: Techniques and Applications

    SciTech Connect

    MacLellan, Ryan

    2011-04-27

    The role of neutron activation analysis in low-energy low-background experimentsis discussed in terms of comparible methods. Radiochemical neutron activation analysis is introduce. The procedure of instrumental neutron activation analysis is detailed especially with respect to the measurement of trace amounts of natural radioactivity. The determination of reactor neutron spectrum parameters required for neutron activation analysis is also presented.

  17. RST (Robust Satellite Techniques) analysis for monitoring earth emitted radiation in seismically active area of California (US): a long term (2006-2011) analysis of GOES-W/IMAGER thermal data

    NASA Astrophysics Data System (ADS)

    Tramutoli, V.; Armandi, B.; Filizzola, C.; Genzano, N.; Lisi, M.; Paciello, R.; Pergola, N.

    2014-12-01

    More than ten years of applications of the RST (Robust Satellite Techniques) methodology for monitoring earthquake prone area by using satellite TIR(Thermal InfraRed) data, have shown the ability of this approach to discern anomalous TIR signals possibly associated to seismic activity from normal fluctuations of Earth's thermal emission related to other causes independent on the earthquake occurrence. The RST approach was already tested in the case of tens of earthquakes occurred in different continents (Europe, Asia, America and Africa), in various geo-tectonic settings (compressive, extensional and transcurrent) and with a wide range of magnitudes (from 4.0 to 7.9), by analyzing time series of TIR images acquired by sensors on board of polar (like NOAA/AVHRR, EOS/MODIS) and geostationary satellites (like MFG/MVIRI, MSG/SEVIRI, GOES/IMAGER). In addition RST method has been independently tested by several researchers around the world as well as in the framework of several projects funded by different national space agencies (like the Italian ASI, the U.S. NASA and the German DLR) and recently during the EC-FP7 projectPRE-EARTHQUAKES (www.pre-earthquakes.org),which was devoted to study the earthquake precursors using satellite techniques. This paper will show the results of RST analysis on 6 years (2006-2011)of TIR satellite record collected by GOES-W/IMAGER over Southern part United State (California).Results will be discussed particularly in the prospective of an integrated approach devoted to systematically collectand analyze in real-time, independent observations for a time-Dependent Assessment of Seismic Hazard (t-DASH).

  18. A diagnostic technique used to obtain cross range radiation centers from antenna patterns

    NASA Technical Reports Server (NTRS)

    Lee, T. H.; Burnside, W. D.

    1988-01-01

    A diagnostic technique to obtain cross range radiation centers based on antenna radiation patterns is presented. This method is similar to the synthetic aperture processing of scattered fields in the radar application. Coherent processing of the radiated fields is used to determine the various radiation centers associated with the far-zone pattern of an antenna for a given radiation direction. This technique can be used to identify an unexpected radiation center that creates an undesired effect in a pattern; on the other hand, it can improve a numerical simulation of the pattern by identifying other significant mechanisms. Cross range results for two 8' reflector antennas are presented to illustrate as well as validate that technique.

  19. Radiation dose reduction in computed tomography: techniques and future perspective

    PubMed Central

    Yu, Lifeng; Liu, Xin; Leng, Shuai; Kofler, James M; Ramirez-Giraldo, Juan C; Qu, Mingliang; Christner, Jodie; Fletcher, Joel G; McCollough, Cynthia H

    2011-01-01

    Despite universal consensus that computed tomography (CT) overwhelmingly benefits patients when used for appropriate indications, concerns have been raised regarding the potential risk of cancer induction from CT due to the exponentially increased use of CT in medicine. Keeping radiation dose as low as reasonably achievable, consistent with the diagnostic task, remains the most important strategy for decreasing this potential risk. This article summarizes the general technical strategies that are commonly used for radiation dose management in CT. Dose-management strategies for pediatric CT, cardiac CT, dual-energy CT, CT perfusion and interventional CT are specifically discussed, and future perspectives on CT dose reduction are presented. PMID:22308169

  20. Nuclear Technology Series. Course 20: Radiation Monitoring Techniques (Radiochemical).

    ERIC Educational Resources Information Center

    Center for Occupational Research and Development, Inc., Waco, TX.

    This technical specialty course is one of thirty-five courses designed for use by two-year postsecondary institutions in five nuclear technician curriculum areas: (1) radiation protection technician, (2) nuclear instrumentation and control technician, (3) nuclear materials processing technician, (4) nuclear quality-assurance/quality-control…

  1. Probing Radiation Damage in Plutonium Alloys with Multiple Measurement Techniques

    SciTech Connect

    McCall, S K; Fluss, M J; Chung, B W

    2010-04-21

    A material subjected to radiation damage will usually experience changes in its physical properties. Measuring these changes in the physical properties provides a basis to study radiation damage in a material which is important for a variety of real world applications from reactor materials to semiconducting devices. When investigating radiation damage, the relative sensitivity of any given property can vary considerably based on the concentration and type of damage present as well as external parameters such as the temperature and starting material composition. By measuring multiple physical properties, these differing sensitivities can be leveraged to provide greater insight into the different aspects of radiation damage accumulation, thereby providing a broader understanding of the mechanisms involved. In this report, self-damage from {alpha}-particle decay in Pu is investigated by measuring two different properties: magnetic susceptibility and resistivity. The results suggest that while the first annealing stage obeys second order chemical kinetics, the primary mechanism is not the recombination of vacancy-interstitial close pairs.

  2. European activities in radiation protection in medicine.

    PubMed

    Simeonov, Georgi

    2015-07-01

    The recently published Council Directive 2013/59/Euratom ('new European Basic Safety Standards', EU BSS) modernises and consolidates the European radiation protection legislation by taking into account the latest scientific knowledge, technological progress and experience with implementing the current legislation and by merging five existing Directives into a single piece of legislation. The new European BSS repeal previous European legislation on which the national systems for radiation protection in medicine of the 28 European Union (EU) Member States are based, including the 96/29/Euratom 'BSS' and the 97/43/Euratom 'Medical Exposure' Directives. While most of the elements of the previous legislation have been kept, there are several legal changes that will have important influence over the regulation and practice in the field all over Europe-these include, among others: (i) strengthening the implementation of the justification principle and expanding it to medically exposed asymptomatic individuals, (ii) more attention to interventional radiology, (iii) new requirements for dose recording and reporting, (iv) increased role of the medical physics expert in imaging, (v) new set of requirements for preventing and following up on accidents and (vi) new set of requirements for procedures where radiological equipment is used on people for non-medical purposes (non-medical imaging exposure). The EU Member States have to enforce the new EU BSS before January 2018 and bring into force the laws, regulations and administrative provisions necessary to comply with it. The European Commission has certain legal obligations and powers to verify the compliance of the national measures with the EU laws and, wherever necessary, issue recommendations to, or open infringement cases against, national governments. In order to ensure timely and coordinated implementation of the new European legal requirements for radiation protection, the Commission is launching several actions

  3. The measurement of radiation exposure of astronauts by radiochemical techniques

    NASA Technical Reports Server (NTRS)

    Brodzinski, R. L.

    1972-01-01

    The principal gamma-ray emitting radioisotopes, produced in the body of astronauts by cosmic-ray bombardment, which have half-lives long enough to be useful for radiation dose evaluation, are Be-7, Na-22, and Na-24. The sodium isotopes were measured in the preflight and postflight urine and feces, and those feces specimens collected during the manned Apollo missions, by analysis of the urine salts and the raw feces in large crystal multidimensional gamma-ray spectrometers. The Be-7 was chemically separated, and its concentration measured in an all NaI (TL), anticoincidence shielded, scintillation well crystal. The astronaut radiation dose in millirads, as determined for the Apollo 7, 8, 9, 10, 11, 12, and 13 missions, was 330, 160, smaller than 315, 870 plus or minus 550, 31, 110, and smaller than 250, respectively.

  4. Optimal control techniques for active noise suppression

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Keeling, S. L.; Silcox, R. J.

    1988-01-01

    Active suppression of noise in a bounded enclosure is considered within the framework of optimal control theory. A sinusoidal pressure field due to exterior offending noise sources is assumed to be known in a neighborhood of interior sensors. The pressure field due to interior controlling sources is assumed to be governed by a nonhomogeneous wave equation within the enclosure and by a special boundary condition designed to accommodate frequency-dependent reflection properties of the enclosure boundary. The form of the controlling sources is determined by considering the steady-state behavior of the system, and it is established that the control strategy proposed is stable and asymptotically optimal.

  5. The impact of radiation hardened by design (RHBD) techniques on the performance of readout integrated circuits in radiation environments

    NASA Astrophysics Data System (ADS)

    Hubbs, John E.; Gramer, Mark E.; Maestas-Jepson, Diana; Dole, Gary A.; Hahn, Allan

    2008-08-01

    The tolerance of a hybrid array (HA) to total ionizing dose (TID) radiation continues to be a major performance consideration for space based imaging systems. In an effort to improve TID performance, HA manufacturers have begun to utilize circuit design techniques to enhance the TID tolerance of readout integrated circuits (ROICs). This paper will report on the radiometric and TID radiation characterizations of a HA that utilizes radiation-hardened-by-design (RHBD) techniques. This paper will not describe the design techniques used. Instead, characterization data are presented that demonstrate a HA TID tolerance of over 25 units of total ionizing dose (UTID). This result is compared with the performance of devices with ROICs processed at commercial foundries that do not make use of RHBD techniques. The HA described in this paper represents a state-of-the-art device; the ROIC was designed to be low noise, high gain, and radiation tolerant. While design techniques were utilized to enhance its TID hardness, no special fabrication processes were used.

  6. Measurement of soil moisture using remote sensing multisensor radiation techniques

    NASA Technical Reports Server (NTRS)

    Waite, W. P. (Principal Investigator)

    1982-01-01

    Theoretical modeling as well as laboratory and field measurement were coupled with analysis of aircraft data obtained from controlled sites in an effort to enhance understanding of the microwave response due to soil moisture so as to specify sensor parameters and develop inversion algorithms. Models to predict the complex dielectric constant were produced which led to the interpretation of the results in terms of a matrix potential rather than simply moisture content. Similar advances were made in the development of coherent and incoherent radiative transfer models and rough surface scattering models.

  7. Radiation exposure induces inflammasome pathway activation in immune cells.

    PubMed

    Stoecklein, Veit M; Osuka, Akinori; Ishikawa, Shizu; Lederer, Madeline R; Wanke-Jellinek, Lorenz; Lederer, James A

    2015-02-01

    Radiation exposure induces cell and tissue damage, causing local and systemic inflammatory responses. Because the inflammasome pathway is triggered by cell death and danger-associated molecular patterns, we hypothesized that the inflammasome may signal acute and chronic immune responses to radiation. Using a mouse radiation model, we show that radiation induces a dose-dependent increase in inflammasome activation in macrophages, dendritic cells, NK cells, T cells, and B cells as judged by cleaved caspase-1 detection in cells. Time course analysis showed the appearance of cleaved caspase-1 in cells by day 1 and sustained expression until day 7 after radiation. Also, cells showing inflammasome activation coexpressed the cell surface apoptosis marker annexin V. The role of caspase-1 as a trigger for hematopoietic cell losses after radiation was studied in caspase-1(-/-) mice. We found less radiation-induced cell apoptosis and immune cell loss in caspase-1(-/-) mice than in control mice. Next, we tested whether uric acid might mediate inflammasome activation in cells by treating mice with allopurinol and discovered that allopurinol treatment completely blocked caspase-1 activation in cells. Finally, we demonstrate that radiation-induced caspase-1 activation occurs by a Nod-like receptor family protein 3-independent mechanism because radiation-exposed Nlrp3(-/-) mice showed caspase-1 activation profiles that were indistinguishable from those of wild-type mice. In summary, our data demonstrate that inflammasome activation occurs in many immune cell types following radiation exposure and that allopurinol prevented radiation-induced inflammasome activation. These results suggest that targeting the inflammasome may help control radiation-induced inflammation. PMID:25539818

  8. Novel Techniques for Exploring the Physics of the Radiation Belts

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Konstantinos

    2012-10-01

    The plasma physics of the Radiation Belts (RB) is a premier scientific topic with important technological implications. A new mission the Radiation Belt Storm Probes (RBSP) will be launched in August, 2012, fully instrumented to explore the RB Physics with emphasis on particle interactions with low frequency plasma waves that control the rates of energetic particle precipitation, acceleration and transport. An important difficulty with passive observation, such as the RBSP, is the ``chicken & egg'' problem. Namely particles drive waves while waves precipitate, accelerate and transport particles. It is a complex, non-linear interaction with multiple feedbacks. The two-satellite coverage provided by RBSP and similar missions does not allow for uniquely identifying cause and effect. A new technology recently developed using ionospheric heaters -- powerful HF transmitters or phased arrays - that allow controlled heating of the ionosphere provides us with means for injecting low frequency waves in the ULF/ELF/VLF range into the RB and using the satellites overflying the heater magnetic flux tubes to diagnose the wave particle interactions. The paper will provide a comprehensive planning of experiments that use the HAARP, Arecibo and SURA heaters in conjunction with RBSP and other satellite missions, such as the Air Force DSX and the Russian RESONANCE, to provide new inroads into the RB physics.

  9. Nonlinear Ultrasonic Techniques to Monitor Radiation Damage in RPV and Internal Components

    SciTech Connect

    Jacobs, Laurence; Kim, Jin-Yeon; Qu, Jisnmin; Ramuhalli, Pradeep; Wall, Joe

    2015-11-02

    The objective of this research is to demonstrate that nonlinear ultrasonics (NLU) can be used to directly and quantitatively measure the remaining life in radiation damaged reactor pressure vessel (RPV) and internal components. Specific damage types to be monitored are irradiation embrittlement and irradiation assisted stress corrosion cracking (IASCC). Our vision is to develop a technique that allows operators to assess damage by making a limited number of NLU measurements in strategically selected critical reactor components during regularly scheduled outages. This measured data can then be used to determine the current condition of these key components, from which remaining useful life can be predicted. Methods to unambiguously characterize radiation related damage in reactor internals and RPVs remain elusive. NLU technology has demonstrated great potential to be used as a material sensor – a sensor that can continuously monitor a material’s damage state. The physical effect being monitored by NLU is the generation of higher harmonic frequencies in an initially monochromatic ultrasonic wave. The degree of nonlinearity is quantified with the acoustic nonlinearity parameter, β, which is an absolute, measurable material constant. Recent research has demonstrated that nonlinear ultrasound can be used to characterize material state and changes in microscale characteristics such as internal stress states, precipitate formation and dislocation densities. Radiation damage reduces the fracture toughness of RPV steels and internals, and can leave them susceptible to IASCC, which may in turn limit the lifetimes of some operating reactors. The ability to characterize radiation damage in the RPV and internals will enable nuclear operators to set operation time thresholds for vessels and prescribe and schedule replacement activities for core internals. Such a capability will allow a more clear definition of reactor safety margins. The research consists of three tasks: (1

  10. Studies on the effect of mobile phone radiation on DNA using laser induced fluorescence technique

    NASA Astrophysics Data System (ADS)

    Vishnu, K.; Nithyaja, B.; Pradeep, C.; Sujith, R.; Mohanan, P.; Nampoori, V. P. N.

    2011-11-01

    In the present study we have investigated the effect of mobile phone radiation on deoxyribonucleic acid by using fluorescence technique. Absorption spectra shows increase in absorption of DNA after exposure to radiation from mobile phone with different SAR values and microwave frequency which give information about unwinding of the DNA double strand. Fluorescence intensity of dye doped DNA solution is getting reduced suggesting that the absorbed energy is used for unwinding of double strand of DNA after irradiating with microwave radiation. Unwinding of the DNA is very sensitive to power of the microwave radiation.

  11. Active radiation hardening technology for fiber-optic source

    NASA Astrophysics Data System (ADS)

    Yang, Yuanhong; Suo, Xinxin; Yang, Mingwei

    2013-09-01

    We demonstrated an active radiation hardening technology for fiber optic source developed for high performance fiber optic gyroscope. The radiation characteristic of erbium-doped fiber was studied experimentally. The radiation induced attenuation (RIA) at 980nm pump light was identified to be the main reason for the degradation and there was photo-bleaching effect in EDF too. A variable parameters control technology was proposed and taken to keep the 980nm and 1550nm light energy stable and high stability and radiation-resistance fiber source with gauss profile spectrum was realized .The source can stand against more than 50 krad (Si) total radiation dose.

  12. An improved technique for global solar radiation estimation using numerical weather prediction

    NASA Astrophysics Data System (ADS)

    Shamim, M. A.; Remesan, R.; Bray, M.; Han, D.

    2015-07-01

    Global solar radiation is the driving force in hydrological cycle especially for evapotranspiration (ET) and is quite infrequently measured. This has led to the reliance on indirect techniques of estimation for data scarce regions. This study presents an improved technique that uses information from a numerical weather prediction (NWP) model (National Centre for Atmospheric Research NCAR's Mesoscale Meteorological model version 5 MM5), for the determination of a cloud cover index (CI), a major factor in the attenuation of the incident solar radiation. The cloud cover index (CI) together with the atmospheric transmission factor (KT) and output from a global clear sky solar radiation were then used for the estimation of global solar radiation for the Brue catchment located in the southwest of England. The results clearly show an improvement in the estimated global solar radiation in comparison to the prevailing approaches.

  13. Techniques for Promoting Active Learning. The Cross Papers.

    ERIC Educational Resources Information Center

    Cross, K. Patricia

    This guide offers suggestions for implementing active learning techniques in the community college classroom. The author argues that, although much of the literature on active learning emphasizes collaboration and small-group learning, active learning does not always involve interaction. It must also involve reflection and self-monitoring of both…

  14. Comparison of data inversion techniques for remotely sensed wide-angle observations of Earth emitted radiation

    NASA Technical Reports Server (NTRS)

    Green, R. N.

    1981-01-01

    The shape factor, parameter estimation, and deconvolution data analysis techniques were applied to the same set of Earth emitted radiation measurements to determine the effects of different techniques on the estimated radiation field. All three techniques are defined and their assumptions, advantages, and disadvantages are discussed. Their results are compared globally, zonally, regionally, and on a spatial spectrum basis. The standard deviations of the regional differences in the derived radiant exitance varied from 7.4 W-m/2 to 13.5 W-m/2.

  15. Radiation safety at accelerator facilities NCRP activities

    NASA Astrophysics Data System (ADS)

    Kase, Kenneth R.

    1997-02-01

    The National Council on Radiation Protection and Measurements (NCRP) has issued 13 reports, dating back to 1949, giving guidance and recommendations for radiation protection at accelerator facilities. There are six current reports on the topics of neutron radiation; facility and shielding design; alarms and access control systems; and equipment design, performance, and use. Scientific Committee 46 (SC 46) is currently overseeing the development of two reports that will provide up-to-date guidance for the design of medical accelerator facilities and shielding. SC 46 has also proposed that a report be written to provide guidance for the design and shielding of industrial accelerator and large irradiator facilities. This paper describes the status and contents of these reports.

  16. Optimized digital filtering techniques for radiation detection with HPGe detectors

    NASA Astrophysics Data System (ADS)

    Salathe, Marco; Kihm, Thomas

    2016-02-01

    This paper describes state-of-the-art digital filtering techniques that are part of GEANA, an automatic data analysis software used for the GERDA experiment. The discussed filters include a novel, nonlinear correction method for ballistic deficits, which is combined with one of three shaping filters: a pseudo-Gaussian, a modified trapezoidal, or a modified cusp filter. The performance of the filters is demonstrated with a 762 g Broad Energy Germanium (BEGe) detector, produced by Canberra, that measures γ-ray lines from radioactive sources in an energy range between 59.5 and 2614.5 keV. At 1332.5 keV, together with the ballistic deficit correction method, all filters produce a comparable energy resolution of ~1.61 keV FWHM. This value is superior to those measured by the manufacturer and those found in publications with detectors of a similar design and mass. At 59.5 keV, the modified cusp filter without a ballistic deficit correction produced the best result, with an energy resolution of 0.46 keV. It is observed that the loss in resolution by using a constant shaping time over the entire energy range is small when using the ballistic deficit correction method.

  17. Utilization of radiation technique on the saccharification and fermentation of biomass

    NASA Astrophysics Data System (ADS)

    Kaetsu, I.; Kumakura, M.; Fujimura, T.; Yoshii, F.; Kojima, T.; Tamada, M.

    The application of irradiation technique to the process of saccharification and subsequent fermentation of cellulosic wastes such as chaff and rice straw to obtain ethanol, was investigated. It was found that when waste raw materials were irradiated by ?-ray or electron beam, they became accessible to the subsequent enzymatic saccharification reaction. Irradiation of 10 7-10 8 Rad was enough for this effect. Some kind of additives reduced necessary dosage for this pretreatment. Cellulase, Trichoderma reesei which produce cellulase, and yeast were immobilized as biocatalysts for biomass conversion by radiation-induced polymerization of glass-forming monomer at low temperature. The immobilized cellulase showed almost same activity of glucose production as the native cellulase. Continuous saccharification reaction was carried out by using the immobilized cellulase. The immobilized Trichoderma reesei and the immobilized yeast showed almost same activity as the intact biocatalysts. It was concluded that the continuous saccharification and subsequent fermentation could be carried out effectively by using the immobilized biocatalysts. Spinach chloroplasts were immobilized by the same method as the first step for the conversion of water into hydrogen gas using solar energy. The immobilized chloroplasts kept the O 2 evolution activity in storage more than 30 days at 4°C. Thermostatility of chloroplasts was also improved greatly by the immobilization.

  18. Measuring the activity of a 51Cr neutrino source based on the gamma-radiation spectrum

    NASA Astrophysics Data System (ADS)

    Gorbachev, V. V.; Gavrin, V. N.; Ibragimova, T. V.; Kalikhov, A. V.; Malyshkin, Yu. M.; Shikhin, A. A.

    2015-12-01

    A technique for the measurement of activities of intense β sources by measuring the continuous gamma-radiation (internal bremsstrahlung) spectra is developed. A method for reconstructing the spectrum recorded by a germanium semiconductor detector is described. A method for the absolute measurement of the internal bremsstrahlung spectrum of 51Cr is presented.

  19. Validation of a technique for estimating outgoing longwave radiation from HIRS radiance observations

    NASA Technical Reports Server (NTRS)

    Ellingson, Robert G.; Lee, Hai-Tien; Yanuk, David; Gruber, Arnold

    1994-01-01

    Simultaneous observations by the Earth Radiation Budget Experiment (ERBE) scanning radiometer and the High-Resolution Infrared Sounder (HIRS) on board the NOAA-9 spacecraft have been used to validate a multispectral technique for estimating the outgoing longwave radiation (OLR) from the earth-atmosphere system. Results from approximately 100 000 collocated observations show that the HIRS technique provides instantaneous OLR estimates that agree with the ERBE observations just as well as different ERBE scanners agree with each other--about 5 W m(exp -2) rms. Although there are differences between the HIRS and ERBE estimates that depend upon the scene type and time of day, the HIRS technique explained more than 99% of the variance of the ERBE observations for both day and night observations. The results suggest that the HIRS OLR technique is a suitable replacement for the Advanced Very High Resolution Radiometer technique now used by the National Oceanic and Atmospheric Administration for operational estimates of the OLR.

  20. Alternative Medicine Techniques Have Non-Linear Effects on Radiation Response and Can Alter the Expression of Radiation Induced Bystander Effects

    PubMed Central

    Mothersill, Carmel; Smith, Richard; Henry, Matthew; Seymour, Colin; Wong, Raimond

    2013-01-01

    Many so-called “alternative medicine” techniques such as Reiki and acupuncture produce very good outcomes for intractable pain and other chronic illnesses but the efficacy is often dismissed as being psychosomatic. However a plausible mechanism does exist i.e. that the treatments alter the electromagnetic fields in living organisms and thereby prevent or reduce activity of neurons which lead to the pain. Low doses of ionising radiation have similar effects on electromagnetic fields and are known to induce signaling cascades in tissues due to ion gradients. To test this hypothesis cell cultures were exposed to Reiki – like and to acupuncture – like treatments, both performed by qualified practitioners. The cells were exposed either before or after the treatment to x-rays and were monitored for production of direct damage or bystander signals. The data suggest that the alternative techniques altered the response of cells to direct irradiation and altered bystander signal mechanisms. We conclude that alternative medicine techniques involving electromagnetic perturbations may modify the response of cells to ionizing radiation. In addition to the obvious implications for mechanistic studies of low dose effects, this could provide a novel target to exploit in radiation protection and in optimizing therapeutic gain during radiotherapy. PMID:23550268

  1. Incorporating Active Learning Techniques into a Genetics Class

    ERIC Educational Resources Information Center

    Lee, W. Theodore; Jabot, Michael E.

    2011-01-01

    We revised a sophomore-level genetics class to more actively engage the students in their learning. The students worked in groups on quizzes using the Immediate Feedback Assessment Technique (IF-AT) and active-learning projects. The IF-AT quizzes allowed students to discuss key concepts in small groups and learn the correct answers in class. The…

  2. Ionizing Radiation Impairs T Cell Activation by Affecting Metabolic Reprogramming

    PubMed Central

    Li, Heng-Hong; Wang, Yi-wen; Chen, Renxiang; Zhou, Bin; Ashwell, Jonathan D.; Fornace, Albert J.

    2015-01-01

    Ionizing radiation has a variety of acute and long-lasting adverse effects on the immune system. Whereas measureable effects of radiation on immune cell cytotoxicity and population change have been well studied in human and animal models, little is known about the functional alterations of the surviving immune cells after ionizing radiation. The objective of this study was to delineate the effects of radiation on T cell function by studying the alterations of T cell receptor activation and metabolic changes in activated T cells isolated from previously irradiated animals. Using a global metabolomics profiling approach, for the first time we demonstrate that ionizing radiation impairs metabolic reprogramming of T cell activation, which leads to substantial decreases in the efficiency of key metabolic processes required for activation, such as glucose uptake, glycolysis, and energy metabolism. In-depth understanding of how radiation impacts T cell function highlighting modulation of metabolism during activation is not only a novel approach to investigate the pivotal processes in the shift of T cell homeostasis after radiation, it also may lead to new targets for therapeutic manipulation in the combination of radiotherapy and immune therapy. Given that appreciable effects were observed with as low as 10 cGy, our results also have implications for low dose environmental exposures. PMID:26078715

  3. Radiation exposure in X-ray-based imaging techniques used in osteoporosis

    PubMed Central

    Adams, Judith E.; Guglielmi, Giuseppe; Link, Thomas M.

    2010-01-01

    Recent advances in medical X-ray imaging have enabled the development of new techniques capable of assessing not only bone quantity but also structure. This article provides (a) a brief review of the current X-ray methods used for quantitative assessment of the skeleton, (b) data on the levels of radiation exposure associated with these methods and (c) information about radiation safety issues. Radiation doses associated with dual-energy X-ray absorptiometry are very low. However, as with any X-ray imaging technique, each particular examination must always be clinically justified. When an examination is justified, the emphasis must be on dose optimisation of imaging protocols. Dose optimisation is more important for paediatric examinations because children are more vulnerable to radiation than adults. Methods based on multi-detector CT (MDCT) are associated with higher radiation doses. New 3D volumetric hip and spine quantitative computed tomography (QCT) techniques and high-resolution MDCT for evaluation of bone structure deliver doses to patients from 1 to 3 mSv. Low-dose protocols are needed to reduce radiation exposure from these methods and minimise associated health risks. PMID:20559834

  4. Direct satellite observations on bremsstrahlung radiation as a technique to investigate its role in meteorological processes

    NASA Technical Reports Server (NTRS)

    Johnson, R. G.; Imhof, W. L.

    1975-01-01

    It was suggested that bremsstrahlung radiation associated with strong auroras (in turn associated with geomagnetic disturbances) may cause increased ionization near the 300-millibar level, which, in turn, leads to the formation of cirrus clouds. These clouds could modify the outgoing black body radiation rates and influence weather patterns. The first satellite observations on bremsstrahlung radiation produced in the atmosphere by precipitating energetic electrons are discussed. This type of observation affords the possibility of directly monitoring the bremsstrahlung energy input to the lower atmosphere over large segments of earth and at frequent intervals. Detailed measurements on the spatial and energy distributions of the bremsstrahlung radiation are feasible with present techniques, and satellite data on widespread bremsstrahlung events are presented and discussed. From comparison of the ion production rates from cosmic rays with those calculated from bremsstrahlung from precipitating energetic electrons, it is concluded that bremsstrahlung radiation is a negligible contributor to the ionization near the 300-millibar level.

  5. Prediction of the solar radiation on the Earth using support vector regression technique

    NASA Astrophysics Data System (ADS)

    Piri, Jamshid; Shamshirband, Shahaboddin; Petković, Dalibor; Tong, Chong Wen; Rehman, Muhammad Habib ur

    2015-01-01

    The solar rays on the surface of Earth is one of the major factor in water resources, environmental and agricultural modeling. The main environmental factors influencing plants growth are temperature, moisture, and solar radiation. Solar radiation is rarely obtained in weather stations; as a result, many empirical approaches have been applied to estimate it by using other parameters. In this study, a soft computing technique, named support vector regression (SVR) has been used to estimate the solar radiation. The data was collected from two synoptic stations with different climate conditions (Zahedan and Bojnurd) during the period of 5 and 7 years, respectively. These data contain sunshine hours, maximum temperature, minimum temperature, average relative humidity and daily solar radiation. In this study, the polynomial and radial basis functions (RBF) are applied as the SVR kernel function to estimate solar radiation. The performance of the proposed estimators is confirmed with the simulation results.

  6. Experimental, theoretical and computational study of frequency upshift of electromagnetic radiation using plasma techniques

    SciTech Connect

    Joshi, C.

    1992-09-01

    This is a second year progress report on Experimental, Theoretical and Computational Study of Frequency Upshift of Electromagnetic Radiation Using Plasma Techniques.'' The highlights are: (I) Ionization fronts have been shown to frequency upshift e.m. radiation by greater than a factor 5. In the experiments, 33 GHz microwave radiation is upshifted to more than 175 GHz using a relativistically propagating ionization front created by a laser beam. (II) A Letter describing the results has been published in Physical Review Letters and an invited'' paper has been submitted to IEEE Trans. in Plasma Science.

  7. Recent Developments in Three Dimensional Radiation Transport Using the Green's Function Technique

    NASA Technical Reports Server (NTRS)

    Rockell, Candice; Tweed, John; Blattnig, Steve R.; Mertens, Christopher J.

    2010-01-01

    In the future, astronauts will be sent into space for longer durations of time compared to previous missions. The increased risk of exposure to dangerous radiation, such as Galactic Cosmic Rays and Solar Particle Events, is of great concern. Consequently, steps must be taken to ensure astronaut safety by providing adequate shielding. In order to better determine and verify shielding requirements, an accurate and efficient radiation transport code based on a fully three dimensional radiation transport model using the Green's function technique is being developed

  8. Imaging techniques for assaying lymphocyte activation in action

    PubMed Central

    Balagopalan, Lakshmi; Sherman, Eilon; Barr, Valarie A.; Samelson, Lawrence E.

    2012-01-01

    Imaging techniques have greatly improved our understanding of lymphocyte activation. Technical advances in spatial and temporal resolution and new labelling tools have enabled researchers to directly observe the activation process. Consequently, research using imaging approaches to study lymphocyte activation has expanded, providing an unprecedented level of cellular and molecular detail in the field. As a result, certain models of lymphocyte activation have been verified, others have been revised and yet others have been replaced with new concepts. In this article, we review the current imaging techniques that are used to assess lymphocyte activation in different contexts, from whole animals to single molecules, and discuss the advantages and potential limitations of these methods. PMID:21179118

  9. Space activities and radiation protection of crew members

    NASA Astrophysics Data System (ADS)

    Straube, Ulrich; Berger, Thomas; Reitz, Guenther; Facius, Rainer; Reiter, Thomas; Kehl, Marcel; Damann, M. D. Volker; Tognini, Michel

    Personnel working as crew in space-based activities e.g. professional astronauts and cosmo-nauts but also -to a certain extend-space flight participants ("space tourists"), demand health and safety considerations that have to include radiation protection measures. The radiation environment that a crew is exposed to during a space flight, differs significantly to that found on earth including commercial aviation, mainly due to the presence of heavy charged particles with great potential for biological damage. The exposure exceeds those routinely received by terrestrial radiation workers. A sequence of activities has to be conducted targeting to mitigate adverse effects of space radiation. Considerable information is available and applied through the joint efforts of the Space Agencies that are involved in the operations of the International Space Station, ISS. This presentation will give an introduction to the current measures for ra-diation monitoring and protection of astronauts of the European Space Agency (ESA). It will include information: on the radiation protection guidelines that shall ensure the proper imple-mentation and execution of radiation protection measures, the operational hardware used for radiation monitoring and personal dosimetry on ISS, as well as information about operational procedures that are applied.

  10. Measurements of the neutron dose equivalent for various radiation qualities, treatment machines and delivery techniques in radiation therapy

    NASA Astrophysics Data System (ADS)

    Hälg, R. A.; Besserer, J.; Boschung, M.; Mayer, S.; Lomax, A. J.; Schneider, U.

    2014-05-01

    In radiation therapy, high energy photon and proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long term health of cancer patients. Due to the high biological effectiveness of neutrons in regards to cancer induction, small neutron doses can be important. This study quantified the neutron doses for different radiation therapy modalities. Most of the reports in the literature used neutron dose measurements free in air or on the surface of phantoms to estimate the amount of neutron dose to the patient. In this study, dose measurements were performed in terms of neutron dose equivalent inside an anthropomorphic phantom. The neutron dose equivalent was determined using track etch detectors as a function of the distance to the isocenter, as well as for radiation sensitive organs. The dose distributions were compared with respect to treatment techniques (3D-conformal, volumetric modulated arc therapy and intensity-modulated radiation therapy for photons; spot scanning and passive scattering for protons), therapy machines (Varian, Elekta and Siemens linear accelerators) and radiation quality (photons and protons). The neutron dose equivalent varied between 0.002 and 3 mSv per treatment gray over all measurements. Only small differences were found when comparing treatment techniques, but substantial differences were observed between the linear accelerator models. The neutron dose equivalent for proton therapy was higher than for photons in general and in particular for double-scattered protons. The overall neutron dose equivalent measured in this study was an order of magnitude lower than the stray dose of a treatment using 6 MV photons, suggesting that the contribution of the secondary neutron dose equivalent to the integral dose of a radiotherapy patient is small.

  11. Measurements of the neutron dose equivalent for various radiation qualities, treatment machines and delivery techniques in radiation therapy.

    PubMed

    Hälg, R A; Besserer, J; Boschung, M; Mayer, S; Lomax, A J; Schneider, U

    2014-05-21

    In radiation therapy, high energy photon and proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long term health of cancer patients. Due to the high biological effectiveness of neutrons in regards to cancer induction, small neutron doses can be important. This study quantified the neutron doses for different radiation therapy modalities. Most of the reports in the literature used neutron dose measurements free in air or on the surface of phantoms to estimate the amount of neutron dose to the patient. In this study, dose measurements were performed in terms of neutron dose equivalent inside an anthropomorphic phantom. The neutron dose equivalent was determined using track etch detectors as a function of the distance to the isocenter, as well as for radiation sensitive organs. The dose distributions were compared with respect to treatment techniques (3D-conformal, volumetric modulated arc therapy and intensity-modulated radiation therapy for photons; spot scanning and passive scattering for protons), therapy machines (Varian, Elekta and Siemens linear accelerators) and radiation quality (photons and protons). The neutron dose equivalent varied between 0.002 and 3 mSv per treatment gray over all measurements. Only small differences were found when comparing treatment techniques, but substantial differences were observed between the linear accelerator models. The neutron dose equivalent for proton therapy was higher than for photons in general and in particular for double-scattered protons. The overall neutron dose equivalent measured in this study was an order of magnitude lower than the stray dose of a treatment using 6 MV photons, suggesting that the contribution of the secondary neutron dose equivalent to the integral dose of a radiotherapy patient is small. PMID:24778349

  12. The effect of data analysis techniques on the interpretation of wide-angle longwave radiation measurements

    NASA Technical Reports Server (NTRS)

    Green, R. N.

    1981-01-01

    Three different data analysis techniques - shape factor, parameter estimation, and deconvolution - have been applied to the same set of satellite radiation measurements to determine their effect on the estimated radiation field. The measurements are from a wide-angle, horizon-to-horizon, nadir-pointing sensor. The shape factor technique reduces each measurement to a radiant exitance at the top of the atmosphere by simple division by a constant. The parameter estimation technique processes all measurements together as a batch and defines the radiant exitance as a least-squares fit to the data. The deconvolution technique takes advantage of the fact that spherical harmonics are the eigenfunctions of the measurement operator. All three techniques are derived, and their assumptions, advantages and disadvantages are discussed. Their results are compared globally, zonally, regionally and on a spatial spectrum basis. All three techniques give comparable results for global parameters; however, results on a regional scale were quite different. The standard deviations of the regional differences in radiant exitance varied from 7.4 to 13.5 W/sq m. Of the three techniques, the parameter estimation technique produced the best regional results and is the choice of the author.

  13. Synergistic-radiation grafting: A novel modification technique for the preparation of biomaterials

    NASA Astrophysics Data System (ADS)

    Müller-Schulte, D.

    1993-10-01

    Radiation grafting was performed using different vinylmonomers and solvents simultaneously to modify polyamide-6 substrates. With the new technique, immunadsorbents and media for affinity chromatography were developed for the separation of low density lipoproteins, IgG antibodies and biotin- antibodies. To increase the biocompatibility of polymers, a graft modification was applied which allowed a totally coherent endothelial cell seeding.

  14. Fluorine gettering by activated charcoal in a radiation environment

    SciTech Connect

    Felker, L.K.; Toth, L.M.

    1988-10-01

    Activated charcoal has been shown to be an effective gettering agent for the fluorine gas that is liberated in a radiation environment. Even though activated charcoal is a commonly used getter, little is known about the radiation stability of the fluorine-charcoal product. This work has shown that not only is the product stable in high gamma radiation fields, but also that radiation enhances the capacity of the charcoal for the fluorine. The most useful application of this work is with the Molten Salt Reactor Experiment (MSRE) fuel salt because the radioactive components (fission products and actinides) cause radiolytic damage to the solid LiF-BeF/sub 2/-ZrF/sub 4/-UF/sub 4/ (64.5, 30.3, 5.0, 0.13 mol %, respectively) resulting in the liberation of fluorine gas. This work has also demonstrated that the maximum damage to the fuel salt by approx.3 /times/ 10/sup 7/ R/h gamma radiation is approximately 2%, at which point the rate of recombination of fluorine with active metal sites within the salt lattice equals the rate of fluorine generation. The enhanced reactivity of the activated charcoal and radiation stability of the product ensures that the gettered fluorine will stay sequestered in the charcoal.

  15. Robust control design techniques for active flutter suppression

    NASA Technical Reports Server (NTRS)

    Ozbay, Hitay; Bachmann, Glen R.

    1994-01-01

    In this paper, an active flutter suppression problem is studied for a thin airfoil in unsteady aerodynamics. The mathematical model of this system is infinite dimensional because of Theodorsen's function which is irrational. Several second order approximations of Theodorsen's function are compared. A finite dimensional model is obtained from such an approximation. We use H infinity control techniques to find a robustly stabilizing controller for active flutter suppression.

  16. Radiation protection in radiologic technology: Apathy versus active involvement

    SciTech Connect

    Franz, K.H.

    1982-11-01

    The lack of active participation in radiation protection is a serious problem in Radiologic Technology today. Underlying the problem is professional apathy. An overview of the historical changes, as well as various recent developments in radiology, accentuate the importance of necessary changes in technologists' attitudes and activities. 22 references.

  17. A novel technique of unilateral percutaneous kyphoplasty achieves effective biomechanical strength and reduces radiation exposure

    PubMed Central

    Zhuang, Yan; Yang, Lei; Li, Haijun; Ren, Yajun; Cao, Xiaojian

    2016-01-01

    Purpose: To develop a novel technique of percutaneous kyphoplasty (PKP) with effective biomechanical strength and lower radiation exposure. Methods: Thirty fresh lumbar vertebrae isolated from six hogs were decalcified and compressed to induce osteoporotic vertebral compression fractures. Kyphoplasty was performed using three different techniques (ten for each group): conventional unilateral approach (group A), conventional bilateral approach (group B) and novel unilateral approach (group C). Biomechanical indexes including Yield load and stiffness were tested before and after kyphoplasty. The anterior height of each vertebral body (AHVB) was measured before compression, after compression and after kyphoplasty. Frequency of C-arm use and volume of bone cement were also recorded in the process. Results: Compared with group A, our novel technique in group C can significantly improve the recovery of AHVB after compression fractures. However, there was no statistical difference between group B and group C. Values of Yield load in both group B and group C were statistically higher than that in group A, however, no significant difference was found between group B and C. Statistical results of stiffness were similar to Yield load. Regarding volume of bone cement and radiation exposure, the novel technique in group C needed more bone cement and fluoroscopy use than in group A but less than in group B. Conclusions: This novel device makes unilateral kyphoplasty feasible, safe and effective. In the premise of guaranteed biomechanical strength, the new technique significantly reduces risk of radiation exposure in kyphoplasty. PMID:27158403

  18. Radiation therapy generates platelet-activating factor agonists

    PubMed Central

    Sahu, Ravi P.; Harrison, Kathleen A.; Weyerbacher, Jonathan; Murphy, Robert C.; Konger, Raymond L.; Garrett, Joy Elizabeth; Chin-Sinex, Helen Jan; Johnston, Michael Edward; Dynlacht, Joseph R.; Mendonca, Marc; McMullen, Kevin; Li, Gengxin; Spandau, Dan F.; Travers, Jeffrey B.

    2016-01-01

    Pro-oxidative stressors can suppress host immunity due to their ability to generate oxidized lipid agonists of the platelet-activating factor-receptor (PAF-R). As radiation therapy also induces reactive oxygen species, the present studies were designed to define whether ionizing radiation could generate PAF-R agonists and if these lipids could subvert host immunity. We demonstrate that radiation exposure of multiple tumor cell lines in-vitro, tumors in-vivo, and human subjects undergoing radiation therapy for skin tumors all generate PAF-R agonists. Structural characterization of radiation-induced PAF-R agonistic activity revealed PAF and multiple oxidized glycerophosphocholines that are produced non-enzymatically. In a murine melanoma tumor model, irradiation of one tumor augmented the growth of the other (non-treated) tumor in a PAF-R-dependent process blocked by a cyclooxygenase-2 inhibitor. These results indicate a novel pathway by which PAF-R agonists produced as a byproduct of radiation therapy could result in tumor treatment failure, and offer important insights into potential therapeutic strategies that could improve the overall antitumor effectiveness of radiation therapy regimens. PMID:26959112

  19. Radiation therapy generates platelet-activating factor agonists.

    PubMed

    Sahu, Ravi P; Harrison, Kathleen A; Weyerbacher, Jonathan; Murphy, Robert C; Konger, Raymond L; Garrett, Joy Elizabeth; Chin-Sinex, Helen Jan; Johnston, Michael Edward; Dynlacht, Joseph R; Mendonca, Marc; McMullen, Kevin; Li, Gengxin; Spandau, Dan F; Travers, Jeffrey B

    2016-04-12

    Pro-oxidative stressors can suppress host immunity due to their ability to generate oxidized lipid agonists of the platelet-activating factor-receptor (PAF-R). As radiation therapy also induces reactive oxygen species, the present studies were designed to define whether ionizing radiation could generate PAF-R agonists and if these lipids could subvert host immunity. We demonstrate that radiation exposure of multiple tumor cell lines in-vitro, tumors in-vivo, and human subjects undergoing radiation therapy for skin tumors all generate PAF-R agonists. Structural characterization of radiation-induced PAF-R agonistic activity revealed PAF and multiple oxidized glycerophosphocholines that are produced non-enzymatically. In a murine melanoma tumor model, irradiation of one tumor augmented the growth of the other (non-treated) tumor in a PAF-R-dependent process blocked by a cyclooxygenase-2 inhibitor. These results indicate a novel pathway by which PAF-R agonists produced as a byproduct of radiation therapy could result in tumor treatment failure, and offer important insights into potential therapeutic strategies that could improve the overall antitumor effectiveness of radiation therapy regimens. PMID:26959112

  20. PARduino: A Simple Device Measuring and Logging Photosynthetically Active Radiation

    NASA Astrophysics Data System (ADS)

    Barnard, H. R.; Findley, M. C.

    2013-12-01

    Photosynthetically Active Radiation (PAR, 400 to 700 nm) is one of the primary controls of forest carbon and water relations. In complex terrain, PAR has high spatial-variability. Given the high cost of commercial datalogging equipment, spatially-distributed measurements of PAR have been typically modeled using geographic coordinates and terrain indices. Here, we present a design for a low cost, field-deployable device for measuring and logging PAR built around an Arduino microcontroller (we named it PARduino). PARduino provides for widely distributed sensor arrays and tests the feasibility of using hobbyist-grade electronics for collecting scientific data. PARduino components include a LiCor quantum sensor, EME Systems signal converter/amplifier, and Sparkfun's Arduino Pro Mini microcontroller. Additional components include a real time clock, a microSD flash memory card, and a custom printed circuit board (PCB). We selected the components with an eye towards ease of assembly. Everything can be connected to the PCB using through-hole soldering techniques. Since the device will be deployed in remote research plots that lack easy access to line power, battery life was also a consideration in the design. Extended deployment is possible because PARduino's software keeps it in a low-power sleep mode until ready to make a measurement. PARduino will be open-source hardware for use and improvement by others.

  1. Development of radiation dose reduction techniques for cadmium zinc telluride detectors in molecular breast imaging

    NASA Astrophysics Data System (ADS)

    O'Connor, Michael K.; Hruska, Carrie B.; Weinmann, Amanda; Manduca, Armando; Rhodes, Deborah J.

    2010-08-01

    Background: Molecular breast imaging (MBI) is a novel breast imaging technique that uses Cadmium Zinc Telluride (CZT) gamma cameras to detect the uptake of Tc-99m sestamibi in breast tumors. Current techniques employ an administered dose of 20-30 mCi Tc-99m, delivering an effective dose of 6.5-10 mSv to the body. This is ~ 5-10 times that of mammography. The goal of this study was to reduce the radiation dose by a factor of 5-10, while maintaining image quality. Methods: A total of 4 dose reduction schemes were evaluated - a) optimized collimation, b) improved utilization of the energy spectrum below the photopeak, c) adaptive geometric mean algorithm developed for combination of images from opposing detectors, and d) non local means filtering (NLMF) for noise reduction and image enhancement. Validation of the various schemes was performed using a breast phantom containing a variety of tumors and containing activity matched to that observed in clinical studies. Results: Development of tungsten collimators with holes matched to the CZT pixels yielded a 2.1-2.9 gain in system sensitivity. Improved utilization of the energy spectra yielded a 1.5-2.0 gain in sensitivity. Development of a modified geometric mean algorithm yielded a 1.4 reduction in image noise, while retaining contrast. Images of the breast phantom demonstrated that a factor of 5 reduction in dose was achieved. Additional refinements to the NLMF should enable an additional factor of 2 reduction in dose. Conclusion: Significant dose reduction in MBI to levels comparable to mammography can be achieved while maintaining image quality.

  2. Applications Of Monte Carlo Radiation Transport Simulation Techniques For Predicting Single Event Effects In Microelectronics

    SciTech Connect

    Warren, Kevin; Reed, Robert; Weller, Robert; Mendenhall, Marcus; Sierawski, Brian; Schrimpf, Ronald

    2011-06-01

    MRED (Monte Carlo Radiative Energy Deposition) is Vanderbilt University's Geant4 application for simulating radiation events in semiconductors. Geant4 is comprised of the best available computational physics models for the transport of radiation through matter. In addition to basic radiation transport physics contained in the Geant4 core, MRED has the capability to track energy loss in tetrahedral geometric objects, includes a cross section biasing and track weighting technique for variance reduction, and additional features relevant to semiconductor device applications. The crucial element of predicting Single Event Upset (SEU) parameters using radiation transport software is the creation of a dosimetry model that accurately approximates the net collected charge at transistor contacts as a function of deposited energy. The dosimetry technique described here is the multiple sensitive volume (MSV) model. It is shown to be a reasonable approximation of the charge collection process and its parameters can be calibrated to experimental measurements of SEU cross sections. The MSV model, within the framework of MRED, is examined for heavy ion and high-energy proton SEU measurements of a static random access memory.

  3. Minimizing occupational and patient radiation exposure using an optimized injection technique

    SciTech Connect

    Holly, A.S.; Stumpf, K.D.; Ortendahl, D.A.; Hattner, R.S.

    1987-12-01

    In an attempt to lower whole-body and hand radiation exposure to the technologist and decrease the number of infiltrated doses, this laboratory instituted a cold start method for radionuclide injection. The authors then compared the radiation dosimetry readings for a period before and after instituting the method. The finger ring exposures and whole-body exposures were compared. The exposure to the technologist's hands was reduced by 56% and to the technologist's body by 28%. Detectable extravasation of the dose was reduced from 64% to 9%. The recommend the use of this technique for all nuclear medicine departments.

  4. Body radiation exposure in breast cancer radiotherapy: Impact of breast IMRT and virtual wedge compensation techniques

    SciTech Connect

    Woo, Tony; Pignol, Jean-Philippe . E-mail: Jean-Philippe.Pignol@sw.ca; Rakovitch, Eileen; Vu, Toni; Hicks, Deanna; O'Brien, Peter; Pritchard, Kathleen

    2006-05-01

    Purpose: Recent reports demonstrate a dramatically increased rate of secondary leukemia for breast cancer patients receiving adjuvant high-dose anthracycline and radiotherapy, and that radiation is an independent factor for the development of leukemia. This study aimed to evaluate the radiation body exposure during breast radiotherapy and to characterize the factors associated with an increased exposure. Patients and Methods: In a prospective cohort of 120 women, radiation measurements were taken from four sites on the body at the time of adjuvant breast radiotherapy. Multiple regression analysis was performed to analyze patient and treatment factors associated with the amount of scattered radiation. Results: For standard 50 Gy breast radiotherapy, the minimal dose received by abdominal organs is on average 0.45 Gy, ranging from 0.06 to 1.55 Gy. The use of physical wedges as a compensation technique was the most significant factor associated with increased scattered dose (p < 0.001), resulting in approximately three times more exposure compared with breast intensity-modulated radiation therapy (IMRT) and dynamic wedge. Conclusions: The amount of radiation that is scattered to a patient's body is consistent with exposure reported to be associated with excess of leukemia. In accordance with the As Low As Reasonably Achievable (ALARA) principle, we recommend using breast IMRT or virtual wedging for the radiotherapy of breast cancer receiving high-dose anthracycline chemotherapy.

  5. Techniques to reduce radiation for patients and operators during aortic endografting.

    PubMed

    Resch, Timothy A; Törnqvist, Per; Sonesson, Björn; Dias, Nuno V

    2016-04-01

    Endovascular aortic repair of aortic pathologies has become widely spread among vascular surgeons. Much focus has been directed at perfecting and developing endovascular procedures to treat evermore complex issues. Much less focus has been directed at the radiation hazards to patients as well as operators and staff when such procedures are performed. Radiation exposure must be used according to the ALARA (As Low As Reasonably Achievable) principle to avoid short- and long-term negative side effects. Modern imaging technology offers many technological developments to reduce radiation such as low-dose programs, pulsed imaging, flat-panel technology and advanced intraoperative imaging techniques. But beside this, simple measures, based on the understanding of radiation exposure, can easily be implemented in everyday standard practice. Appropriate shielding of patients and staff, using adjuncts to be able to keep a safe distance to the radiation source and avoiding working with inappropriate C-arm angulations should be used routinely. Continued education of vascular surgeons is imperative to implement changes in practice to reduce radiation exposure. PMID:26698035

  6. Quantification of cellulase activity using the quartz crystal microbalance technique.

    PubMed

    Hu, Gang; Heitmann, John A; Rojas, Orlando J

    2009-03-01

    The development of more efficient utilization of biomass has received increased attention in recent years. Cellulases play an important role in processing biomass through advanced biotechnological approaches. Both the development and the application of cellulases require an understanding of the activities of these enzymes. A new method to determine the activity of cellulase has been developed using a quartz crystal microbalance (QCM) technique. We compare the results from this technique with those from the IUPAC (International Union of Pure and Applied Chemistry) dinitrosalicylic acid (DNS) standard method and also from biccinchoninic acid and ion chromatography methods. It is shown that the QCM technique provides results closer to those obtained by measuring the actual reducing sugars. The elimination of the use of color development in the standard redox methods makes the QCM platform easier to implement; it also allows more flexibility in terms of the nature of the substrate. Finally, validation of the proposed method was carried out by relating the crystallinity of different substrates to the cellulase activity. Numerical values of cellulase activities measured with the QCM method showed that celluloses with higher crystallinity indices were hydrolyzed slower and to a lower extent than those of lower crystallinity indices for the cellulase mixtures examined. PMID:19203287

  7. Radiation-pressure-supported obscuring tori around active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Pier, Edward A.; Krolik, Julian H.

    1992-01-01

    Radiation pressure acting on dust grains can support the vertical thickness of the obscuring tori believed to exist in active galactic nuclei. Using the results of 2D radiation transfer calculations, we evaluate the radiation force acting on these tori. We find that on the inner edge of the torus the radiation force is about 350 l(E) times the gravitational force of the nucleus, where l(E) is the Eddington ratio. Beyond a few torus heights from the inner edge, the radiation force is negligible with respect to gravity. However, between these two extremes lies a region of considerable size where the ratio of radiation force to gravity is nearly constant and can be of order unity for l(E) about 0.1. If the distribution of material within the torus is sufficiently lumpy, there is a significant time-varying component to the radiation force. This drives the random motions of the constituent clouds, thickening the torus at lower values of l(E).

  8. Spectromicroscopy of Polymers: Comparison of Radiation Damage with Electron and Photon Core Excitation Spectroscopy Techniques

    NASA Astrophysics Data System (ADS)

    Ade, H.; Smith, A. P.; Rightor, E. G.; Hitchcock, A. P.; Urquhart, S.; Leapman, R.

    1997-03-01

    Core excitation microspectroscopy has become a powerful tool for the characterization of polymeric materials due to its sensitivity to chemical functionality. However, the excitations utilized in electron energy loss spectroscopy performed in a scanning transmission electron microscope (TEM-EELS) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy can introduce radiation damage and chemically modify the sample. In order to understand the radiation damage associated with TEM-EELS and NEXAFS spectroscopy we have studied the radiation damage of the common polymer poly(ethylene terephthalate) (PET) as exhibited by changes in the acquired C K-edge excitation spectra. By fitting gaussian functions to the spectral intensity changes as a function of dose, we have determined the critical radiation dose of PET for both NEXAFS spectroscopy and TEM-EELS under typical operating conditions. This critical radiation dose for TEM-EELS is found to be 1.7 ± 0.2 x 10^8 grey (1.7 ± 0.2 x 10^4 Mrad) compared to a critical radiation dose for NEXAFS spectroscopy of 1.4 ± 0.7 x 10^9 grey (1.4 ± 0.7 x 10^5 Mrad). By considering the G factors of the two techniques and the critical radiation dose, a rule of thumb was derived that indicates that with typical present operating conditions, NEXAFS spectroscopy can analyze areas 500 times smaller than TEM-EELS given the same amount of radiation damage. Work supported by: NSF Young Investigator Award (DMR-9458060) and Dow Chemical

  9. Radiation-driven Outflows from and Radiative Support in Dusty Tori of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Chan, Chi-Ho; Krolik, Julian H.

    2016-07-01

    Substantial evidence points to dusty, geometrically thick tori obscuring the central engines of active galactic nuclei (AGNs), but so far no mechanism satisfactorily explains why cool dust in the torus remains in a puffy geometry. Near-Eddington infrared (IR) and ultraviolet (UV) luminosities coupled with high dust opacities at these frequencies suggest that radiation pressure on dust can play a significant role in shaping the torus. To explore the possible effects of radiation pressure, we perform three-dimensional radiative hydrodynamics simulations of an initially smooth torus. Our code solves the hydrodynamics equations, the time-dependent multi–angle group IR radiative transfer (RT) equation, and the time-independent UV RT equation. We find a highly dynamic situation. IR radiation is anisotropic, leaving primarily through the central hole. The torus inner surface exhibits a break in axisymmetry under the influence of radiation and differential rotation; clumping follows. In addition, UV radiation pressure on dust launches a strong wind along the inner surface; when scaled to realistic AGN parameters, this outflow travels at ˜ 5000 {(M/{10}7{M}ȯ )}1/4 {[{L}{UV}/(0.1{L}{{E}})]}1/4 {km} {{{s}}}-1 and carries ˜ 0.1 {(M/{10}7{M}ȯ )}3/4 {[{L}{UV}/(0.1{L}{{E}})]}3/4 M ⊙ yr‑1, where M, {L}{UV}, and {L}{{E}} are the mass, UV luminosity, and Eddington luminosity of the central object respectively.

  10. Radiation-driven Outflows from and Radiative Support in Dusty Tori of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Chan, Chi-Ho; Krolik, Julian H.

    2016-07-01

    Substantial evidence points to dusty, geometrically thick tori obscuring the central engines of active galactic nuclei (AGNs), but so far no mechanism satisfactorily explains why cool dust in the torus remains in a puffy geometry. Near-Eddington infrared (IR) and ultraviolet (UV) luminosities coupled with high dust opacities at these frequencies suggest that radiation pressure on dust can play a significant role in shaping the torus. To explore the possible effects of radiation pressure, we perform three-dimensional radiative hydrodynamics simulations of an initially smooth torus. Our code solves the hydrodynamics equations, the time-dependent multi–angle group IR radiative transfer (RT) equation, and the time-independent UV RT equation. We find a highly dynamic situation. IR radiation is anisotropic, leaving primarily through the central hole. The torus inner surface exhibits a break in axisymmetry under the influence of radiation and differential rotation; clumping follows. In addition, UV radiation pressure on dust launches a strong wind along the inner surface; when scaled to realistic AGN parameters, this outflow travels at ∼ 5000 {(M/{10}7{M}ȯ )}1/4 {[{L}{UV}/(0.1{L}{{E}})]}1/4 {km} {{{s}}}-1 and carries ∼ 0.1 {(M/{10}7{M}ȯ )}3/4 {[{L}{UV}/(0.1{L}{{E}})]}3/4 M ⊙ yr‑1, where M, {L}{UV}, and {L}{{E}} are the mass, UV luminosity, and Eddington luminosity of the central object respectively.

  11. A new polarimetric active radar calibrator and calibration technique

    NASA Astrophysics Data System (ADS)

    Tang, Jianguo; Xu, Xiaojian

    2015-10-01

    Polarimetric active radar calibrator (PARC) is one of the most important calibrators with high radar cross section (RCS) for polarimetry measurement. In this paper, a new double-antenna polarimetric active radar calibrator (DPARC) is proposed, which consists of two rotatable antennas with wideband electromagnetic polarization filters (EMPF) to achieve lower cross-polarization for transmission and reception. With two antennas which are rotatable around the radar line of sight (LOS), the DPARC provides a variety of standard polarimetric scattering matrices (PSM) through the rotation combination of receiving and transmitting polarization, which are useful for polarimatric calibration in different applications. In addition, a technique based on Fourier analysis is proposed for calibration processing. Numerical simulation results are presented to demonstrate the superior performance of the proposed DPARC and processing technique.

  12. Radiative-neutron-capture gamma-ray analysis by a linear combination technique

    USGS Publications Warehouse

    Tanner, A.B.; Bhargava, R.C.; Senftle, F.E.; Brinkerhoff, J.M.

    1972-01-01

    The linear combination technique, when applied to a gamma-ray spectrum, gives a single number indicative of the extent to which the spectral lines of a sought element are present in a complex spectrum. Spectra are taken of the sought element and of various other substances whose spectra interfere with that of the sought element. A weighting function is then computed for application to spectra of unknown materials. The technique was used to determine calcium by radiative-neutron-capture gamma-ray analysis in the presence of interfering elements, notably titanium, and the results were compared with those for two popular methods of peak area integration. Although linearity of response was similar for the methods, the linear combination technique was much better at rejecting interferences. For analyses involving mixtures of unknown composition the technique consequently offers improved sensitivity. ?? 1972.

  13. A measurement technique to determine the calibration accuracy of an electromagnetic tracking system to radiation isocenter

    SciTech Connect

    Litzenberg, Dale W.; Gallagher, Ian; Masi, Kathryn J.; Lee, Choonik; Prisciandaro, Joann I.; Hamstra, Daniel A.; Ritter, Timothy; Lam, Kwok L.

    2013-08-15

    Purpose: To present and characterize a measurement technique to quantify the calibration accuracy of an electromagnetic tracking system to radiation isocenter.Methods: This technique was developed as a quality assurance method for electromagnetic tracking systems used in a multi-institutional clinical hypofractionated prostate study. In this technique, the electromagnetic tracking system is calibrated to isocenter with the manufacturers recommended technique, using laser-based alignment. A test patient is created with a transponder at isocenter whose position is measured electromagnetically. Four portal images of the transponder are taken with collimator rotations of 45° 135°, 225°, and 315°, at each of four gantry angles (0°, 90°, 180°, 270°) using a 3 × 6 cm{sup 2} radiation field. In each image, the center of the copper-wrapped iron core of the transponder is determined. All measurements are made relative to this transponder position to remove gantry and imager sag effects. For each of the 16 images, the 50% collimation edges are identified and used to find a ray representing the rotational axis of each collimation edge. The 16 collimator rotation rays from four gantry angles pass through and bound the radiation isocenter volume. The center of the bounded region, relative to the transponder, is calculated and then transformed to tracking system coordinates using the transponder position, allowing the tracking system's calibration offset from radiation isocenter to be found. All image analysis and calculations are automated with inhouse software for user-independent accuracy. Three different tracking systems at two different sites were evaluated for this study.Results: The magnitude of the calibration offset was always less than the manufacturer's stated accuracy of 0.2 cm using their standard clinical calibration procedure, and ranged from 0.014 to 0.175 cm. On three systems in clinical use, the magnitude of the offset was found to be 0.053 ± 0.036, 0

  14. Novel On-wafer Radiation Pattern Measurement Technique for MEMS Actuator Based Reconfigurable Patch Antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2002-01-01

    The paper presents a novel on-wafer, antenna far field pattern measurement technique for microelectromechanical systems (MEMS) based reconfigurable patch antennas. The measurement technique significantly reduces the time and the cost associated with the characterization of printed antennas, fabricated on a semiconductor wafer or dielectric substrate. To measure the radiation patterns, the RF probe station is modified to accommodate an open-ended rectangular waveguide as the rotating linearly polarized sampling antenna. The open-ended waveguide is attached through a coaxial rotary joint to a Plexiglas(Trademark) arm and is driven along an arc by a stepper motor. Thus, the spinning open-ended waveguide can sample the relative field intensity of the patch as a function of the angle from bore sight. The experimental results include the measured linearly polarized and circularly polarized radiation patterns for MEMS-based frequency reconfigurable rectangular and polarization reconfigurable nearly square patch antennas, respectively.

  15. Novel On-Wafer Radiation Pattern Measurement Technique for MEMS Actuator Based Reconfigurable Patch Antennas

    NASA Astrophysics Data System (ADS)

    Simons, Rainee N.

    2002-10-01

    The paper presents a novel on-wafer, antenna far field pattern measurement technique for microelectromechanical systems (MEMS) based reconfigurable patch antennas. The measurement technique significantly reduces the time and the cost associated with the characterization of printed antennas, fabricated on a semiconductor wafer or dielectric substrate. To measure the radiation patterns, the RF probe station is modified to accommodate an open-ended rectangular waveguide as the rotating linearly polarized sampling antenna. The open-ended waveguide is attached through a coaxial rotary joint to a Plexiglas(Trademark) arm and is driven along an arc by a stepper motor. Thus, the spinning open-ended waveguide can sample the relative field intensity of the patch as a function of the angle from bore sight. The experimental results include the measured linearly polarized and circularly polarized radiation patterns for MEMS-based frequency reconfigurable rectangular and polarization reconfigurable nearly square patch antennas, respectively.

  16. Active vibration control techniques for flexible space structures

    NASA Technical Reports Server (NTRS)

    Parlos, Alexander G.; Jayasuriya, Suhada

    1990-01-01

    Two proposed control system design techniques for active vibration control in flexible space structures are detailed. Control issues relevant only to flexible-body dynamics are addressed, whereas no attempt was made to integrate the flexible and rigid-body spacecraft dynamics. Both of the proposed approaches revealed encouraging results; however, further investigation of the interaction of the flexible and rigid-body dynamics is warranted.

  17. Prompt gamma activation analysis: An old technique made new

    SciTech Connect

    English, Jerry; Firestone, Richard; Perry, Dale; Leung, Ka-Ngo; Reijonen, Jani; Garabedian, Glenn; Bandong, Bryan; Molnar, Gabor; Revay, Zsolt

    2002-12-01

    The long list of contributors to the prompt gamma activation analysis (PGAA) project is important because it highlights the broad cast of active PGAA researchers from various facilities and backgrounds. PGAA is basically a simple process in principle that was traditionally difficult in application. It is an old technique that has for years been tied to and associated exclusively with nuclear reactor facilities, which has limited its acceptance as a general, analytical tool for identifying and quantifying elements or, more precisely, isotopes, whether radioactive or nonradioactive. Field use was not a viable option.

  18. Discrete ordinates-Monte Carlo coupling: A comparison of techniques in NERVA radiation analysis

    NASA Technical Reports Server (NTRS)

    Lindstrom, D. G.; Normand, E.; Wilcox, A. D.

    1972-01-01

    In the radiation analysis of the NERVA nuclear rocket system, two-dimensional discrete ordinates calculations are sufficient to provide detail in the pressure vessel and reactor assembly. Other parts of the system, however, require three-dimensional Monte Carlo analyses. To use these two methods in a single analysis, a means of coupling was developed whereby the results of a discrete ordinates calculation can be used to produce source data for a Monte Carlo calculation. Several techniques for producing source detail were investigated. Results of calculations on the NERVA system are compared and limitations and advantages of the coupling techniques discussed.

  19. Application of the TLD albedo technique for monitoring and interpretation of neutron stray radiation fields

    NASA Astrophysics Data System (ADS)

    Piesch, E.; Burgkhardt, B.

    1980-09-01

    A single sphere albedo technique with TLD 600/TLD 700 detectors has been applied in neutron monitoring to calibrate albedo dosimeters and to interpret neutron stray radiation fields in terms of neutron dose equivalent separated for the energy groups below 0.4 eV, 0.4-10 keV and 10 keV-10 MeV, and Eeff for fast neutrons. The paper describes the technique for field and personnel monitoring under the aspect of an on-line computer program for data recording and processing.

  20. Collisional-radiative switching - A powerful technique for converging non-LTE calculations

    NASA Technical Reports Server (NTRS)

    Hummer, D. G.; Voels, S. A.

    1988-01-01

    A very simple technique has been developed to converge statistical equilibrium and model atmospheric calculations in extreme non-LTE conditions when the usual iterative methods fail to converge from an LTE starting model. The proposed technique is based on a smooth transition from a collision-dominated LTE situation to the desired non-LTE conditions in which radiation dominates, at least in the most important transitions. The proposed approach was used to successfully compute stellar models with He abundances of 0.20, 0.30, and 0.50; Teff = 30,000 K, and log g = 2.9.

  1. Spectral radiative heat transfer in coal furnaces using a hybrid technique

    SciTech Connect

    Ahluwalia, R.K.; Im, K.H.

    1994-03-01

    A hybrid technique has been developed to solve three-dimensional spectral radiation transport equations for absorbing, emitting and anisotropically scattering media. An optimal mix of computational speed and accuracy is obtained by combining the discrete ordinate method (S{sub 4}), modified differential approximation (MDA) and P{sub 1} approximation for use in different range of optical thicknesses. The technique is used in conjunction with a char burnout model and spectroscopic data for H{sub 2}O, CO{sub 2}, CO, char, soot and ash to determine the influence of ash composition, ash content and coal preparation on furnace heat absorption.

  2. Chorus wave-normal statistics in the Earth's radiation belts from ray tracing technique

    NASA Astrophysics Data System (ADS)

    Breuillard, H.; Zaliznyak, Y.; Krasnoselskikh, V.; Agapitov, O.; Artemyev, A.; Rolland, G.

    2012-08-01

    Discrete ELF/VLF (Extremely Low Frequency/Very Low Frequency) chorus emissions are one of the most intense electromagnetic plasma waves observed in radiation belts and in the outer terrestrial magnetosphere. These waves play a crucial role in the dynamics of radiation belts, and are responsible for the loss and the acceleration of energetic electrons. The objective of our study is to reconstruct the realistic distribution of chorus wave-normals in radiation belts for all magnetic latitudes. To achieve this aim, the data from the electric and magnetic field measurements onboard Cluster satellite are used to determine the wave-vector distribution of the chorus signal around the equator region. Then the propagation of such a wave packet is modeled using three-dimensional ray tracing technique, which employs K. Rönnmark's WHAMP to solve hot plasma dispersion relation along the wave packet trajectory. The observed chorus wave distributions close to waves source are first fitted to form the initial conditions which then propagate numerically through the inner magnetosphere in the frame of the WKB approximation. Ray tracing technique allows one to reconstruct wave packet properties (electric and magnetic fields, width of the wave packet in k-space, etc.) along the propagation path. The calculations show the spatial spreading of the signal energy due to propagation in the inhomogeneous and anisotropic magnetized plasma. Comparison of wave-normal distribution obtained from ray tracing technique with Cluster observations up to 40° latitude demonstrates the reliability of our approach and applied numerical schemes.

  3. Gamma radiation influence on silica optical fibers measured by optical backscatter reflectometry and Brillouin sensing technique

    NASA Astrophysics Data System (ADS)

    Wosniok, A.; Sporea, D.; Neguţ, D.; Krebber, K.

    2016-05-01

    We have studied the influence of gamma rays on physical properties of different commercially available silica optical fibers stepwise irradiated up to a total dose of 100 kGy. The detection of radiation-induced changes in silica glass offers the possibility of using selected optical fibers as distributed radiation sensors. The measurements performed by us were based on optical backscatter reflectometry and Brillouin distributed sensing. The measurement methods enable an analysis of radiation-induced modification of the group refractive index and density of the optical fibers. The most distinct physical effect observed by us concerns the increase of the optical attenuation with rising total radiation doses. Quantitative measurement results indicate a crucial impact of fiber dopants on radiation-induced physical and sensory characteristics of silica optical fibers affected by differences in fiber fabrication techniques. Based on the obtained results, the suitability of distributed Brillouin sensing for dosimetry applications seems to be improved by modifying the refractive index profile of the fiber core.

  4. Postoperative vaginal radiation in endometrial cancer using a remote afterloading technique

    SciTech Connect

    Mandell, L.; Nori, D.; Anderson, L.; Hilaris, B.

    1985-03-01

    Carcinoma of the endometrium is the most common malignancy of the female genital tract. In early stage endometrial cancer, surgery remains the primary mode of treatment while radiation therapy plays an adjuvant role. Prophylactic vaginal radiation has been shown to reduce significantly the incidence of vaginal recurrences. Between the years 1969-1976, 330 patients with FIGO Stages I and II endometrial cancer were treated according to a standard departmental policy in which 40 Gy of external radiation was given to high risk Stage I and II patients in combination with surgery and intravaginal radiation. With this regimen, the mucosal surface received a total equivalent dose of 40 Gy. These treatments were given on an outpatient basis without the need for any sedation or analgesics. The minimum follow-up was 5 years, with a median follow-up of 8.5 years. The overall pelvic and/or vaginal recurrence rate was 2.7%. The incidence of vaginal complications was 3.7%. The advantages of a remote after loading technique in delivering vaginal vault radiation in endometrial cancer are discussed.

  5. Activating PTEN by COX-2 inhibitors antagonizes radiation-induced AKT activation contributing to radiosensitization

    SciTech Connect

    Meng, Zhen; Gan, Ye-Hua

    2015-05-01

    Radiotherapy is still one of the most effective nonsurgical treatments for many tumors. However, radioresistance remains a major impediment to radiotherapy. Although COX-2 inhibitors can induce radiosensitization, the underlying mechanism is not fully understood. In this study, we showed that COX-2 selective inhibitor celecoxib enhanced the radiation-induced inhibition of cell proliferation and apoptosis in HeLa and SACC-83 cells. Treatment with celecoxib alone dephosphorylated phosphatase and tensin homolog deleted on chromosome ten (PTEN), promoted PTEN membrane translocation or activation, and correspondingly dephosphorylated or inactivated protein kinase B (AKT). By contrast, treatment with radiation alone increased PTEN phosphorylation, inhibited PTEN membrane translocation and correspondingly activated AKT in the two cell lines. However, treatment with celecoxib or another COX-2 selective inhibitor (valdecoxib) completely blocked radiation-induced increase of PTEN phosphorylation, rescued radiation-induced decrease in PTEN membrane translocation, and correspondingly inactivated AKT. Moreover, celecoxib could also upregulate PTEN protein expression by downregulating Sp1 expression, thereby leading to the activation of PTEN transcription. Our results suggested that COX-2 inhibitors could enhance radiosensitization at least partially by activating PTEN to antagonize radiation-induced AKT activation. - Highlights: • COX-2 inhibitor, celecoxib, could enhance radiosensitization. • Radiation induced PTEN inactivation (phosphorylation) and AKT activation. • COX-2 inhibitor induced PTEN expression and activation, and inactivated AKT. • COX-2 inhibitor enhanced radiosensitization through activating PTEN.

  6. Active cleaning techniques for removing contamination from optical surfaces in space

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B.

    1973-01-01

    Research in developing an active cleaning technique for removing contaminants from optical surfaces in space is reported. In situ contamination/cleaning experiments were conducted on gold and platimum coated mirrors, which were contaminated by exposure to UV radiation in a 1,3, butadiene environment. Argon and oxygen plasma exposure cleaned the mirrors equally well. Silicone cleaning experiments were also conducted. Exposure of the contaminated mirrors to helium, oxygen, and hydrogen plasmas restored the reflectance at the shorter wavelengths and degraded it at the longer wavelengths.

  7. Ecological Insights from Pelagic Habitats Acquired Using Active Acoustic Techniques.

    PubMed

    Benoit-Bird, Kelly J; Lawson, Gareth L

    2016-01-01

    Marine pelagic ecosystems present fascinating opportunities for ecological investigation but pose important methodological challenges for sampling. Active acoustic techniques involve producing sound and receiving signals from organisms and other water column sources, offering the benefit of high spatial and temporal resolution and, via integration into different platforms, the ability to make measurements spanning a range of spatial and temporal scales. As a consequence, a variety of questions concerning the ecology of pelagic systems lend themselves to active acoustics, ranging from organism-level investigations and physiological responses to the environment to ecosystem-level studies and climate. As technologies and data analysis methods have matured, the use of acoustics in ecological studies has grown rapidly. We explore the continued role of active acoustics in addressing questions concerning life in the ocean, highlight creative applications to key ecological themes ranging from physiology and behavior to biogeography and climate, and discuss emerging avenues where acoustics can help determine how pelagic ecosystems function. PMID:26515810

  8. Ecological Insights from Pelagic Habitats Acquired Using Active Acoustic Techniques

    NASA Astrophysics Data System (ADS)

    Benoit-Bird, Kelly J.; Lawson, Gareth L.

    2016-01-01

    Marine pelagic ecosystems present fascinating opportunities for ecological investigation but pose important methodological challenges for sampling. Active acoustic techniques involve producing sound and receiving signals from organisms and other water column sources, offering the benefit of high spatial and temporal resolution and, via integration into different platforms, the ability to make measurements spanning a range of spatial and temporal scales. As a consequence, a variety of questions concerning the ecology of pelagic systems lend themselves to active acoustics, ranging from organism-level investigations and physiological responses to the environment to ecosystem-level studies and climate. As technologies and data analysis methods have matured, the use of acoustics in ecological studies has grown rapidly. We explore the continued role of active acoustics in addressing questions concerning life in the ocean, highlight creative applications to key ecological themes ranging from physiology and behavior to biogeography and climate, and discuss emerging avenues where acoustics can help determine how pelagic ecosystems function.

  9. Useful intensity: A technique to identify radiating regions on arbitrarily shaped surfaces

    NASA Astrophysics Data System (ADS)

    Corrêa Junior, C. A.; Tenenbaum, R. A.

    2013-03-01

    This work presents a new technique for the computation of the numerical equivalent to the supersonic acoustic intensity, for arbitrarily shaped sound sources. The technique provides therefore the identification of the regions of a noise source that effectively contribute to the sound power radiated into the far field by filtering non-propagating sound waves. The proposed technique is entirely formulated on the vibrating surface. The radiated acoustic power is obtained through a numerical operator that relates it with the superficial normal velocity distribution. The power operator is obtained by using the boundary element method. Such operator, possesses the property of being Hermitian. The advantage of this characteristic is that it has real eigenvalues and their eigenvectors form an orthonormal set for the velocity distribution. It is applied to the power operator the decomposition in eigenvalues and eigenvectors, becoming possible to compute the numerical equivalent to the supersonic intensity, called here as useful intensity, after applying a cutoff criterion to remove the non-propagating components. Some numerical tests confirming the effectiveness of the convergence criterion are presented. Examples of the application of the useful intensity technique in vibrating surfaces such as a plate, a cylinder with flat caps and an automotive muffler are presented and the numerical results are discussed.

  10. Radiation processing in india-current R & D activities

    NASA Astrophysics Data System (ADS)

    Majali, A. B.; Sabharwal, S.

    1995-09-01

    Radiation processing is an area of vigorous activity in today's India. With the indigenous expertise in Co source and irradiator technology, potentially promising applications such as sustained drug delivery systems, vulcanization of natural rubber latex (RVNRL), and degradation of polytetrafluoroethylene (PTFE) are presently investigated. Over the last four years, technologies for RVNRL and PTFE degradation have been scaled upto pilot scale operations, while radiation polymerized polymer systems have been developed for controlled release of certain drugs. With the commissioning of the 2 MeV EB machine in late 1988, a few EB based processes have also been commercially exploited. The paper briefly reviews these and presents the significant results obtained.

  11. Calibration of the active radiation detector for Spacelab-One

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The flight models of the active radiation detector (ARD) for the ENV-01 environmental monitor were calibrated using gamma radiation. Measured sensitivities of the ion chambers were 6.1 + or - 0.3 micron rad per count for ARD S/N1, and 10.4 + or - 0.5 micron rad per count for ARD S/N2. Both were linear over the measured range 0.10 to 500 m/rad hour. The particle counters (proportional counters) were set to respond to approximately 85% of minimum ionizing particles of unit charge passing through them. These counters were also calibrated in the gamma field.

  12. Active thermal extraction of near-field thermal radiation

    NASA Astrophysics Data System (ADS)

    Ding, D.; Kim, T.; Minnich, A. J.

    2016-02-01

    Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at subwavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active scheme to extract these modes to the far field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far field. Our study demonstrates an approach to manipulate thermal radiation that could find applications in thermal management.

  13. Comparison of Various Radiation Therapy Techniques in Breast Cancer Where Target Volume Includes Mammaria Interna Region

    SciTech Connect

    Dogan, Mehmet Hakan; Zincircioglu, Seyit Burhanedtin Zorlu, Faruk

    2009-04-01

    In breast cancer radiotherapy, the internal mammary lymphatic chain is treated in the target volume in a group of patients with high-risk criteria. Because of the variability of the anatomic region and structures in the irradiation field, there are a number of different techniques in breast radiotherapy. While irradiating the target volume, we also consider minimizing the dose to critical structures such as heart, lung, and contralateral breast tissue. In this study, we evaluated the dose distribution of different radiotherapy techniques in patients with left-sided breast cancer who had breast-conserving surgery. A three-dimensional computerized planning system (3DCPS) was used for each patient to compare wide-field, oblique photon-electron, and perpendicular photon-electron techniques in terms of dose homogeneities in the target volume; the doses received by the contralateral breast, heart, and lung; and the coverage of the internal mammary chain. Data from 3DCPS were controlled by the Rando-phantom and thermoluminescence dosimetry. Critical structures were irradiated with acceptable dose percentages in addition to the internal mammary chain with both wide-field and photon-electron techniques. We detected more frequent hot spots in the oblique photon-electron technique than in the other techniques, and this situation necessitated changing the junctions. The wide-field technique was easy to perform and exposed less radiation dose to the heart than photon-electron techniques. In conclusion, we suggest the use of the wide-field technique in breast irradiation when the internal mammary area is in the target volume.

  14. A simulation technique for 3D MR-guided acoustic radiation force imaging

    PubMed Central

    Payne, Allison; de Bever, Josh; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-01-01

    Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation force field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Green’s function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Green’s function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30- and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.028–0.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison

  15. A simulation technique for 3D MR-guided acoustic radiation force imaging

    SciTech Connect

    Payne, Allison; Bever, Josh de; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-02-15

    Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation force field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Green’s function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Green’s function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30- and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.028–0.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison

  16. Insolubilisation of biologically active materials with novel radiation graft copolymers

    NASA Astrophysics Data System (ADS)

    Garnett, J. L.; Jankiewicz, S. V.; Levot, R.; Sangster, D. F.

    The use of radiation grafting to immobilise a typical enzyme, trypsin, is reported. The technique involves radiation grafting to a backbone polymer a monomer containing an appropriate functional group to which the enzyme is bonded. In the present work, p-nitrostyrene has been grafted to representative trunk polymers, polypropylene and PVC, the nitro group in the resulting copolymer converted to the isothiocyanato derivative to which trypsin is attached. Of importance to this insolubilisation process, especially for radiation sensitive backbone polymers, is the inclusion of additives which enhance grafting. A new class of additives which increase the grafting yields is reported using as representative backbone polymers, naturally occurring cellulose and synthetic low density polyethylene. The new additives are specific metal salts such as LiClO 4. The reactivity of these salts in grafting enhancement has been compared with that of mineral acid which has previously been used as an additive to increase grafting yields in both preirradiation and simultaneous techniques. A new model for grafting enhancement in the presence of the metal salts as well as acids is proposed whereby increased grafting yields are attributed to increased partitioning of monomer into the graft region in the presence of ionic solutes. The value of these additives in preparing copolymers suitable for general reagent insolubilisation reactions is discussed.

  17. Technique of radiation polymerization in fine art conservation: a potentially new method of restoration and preservation. [Uv and electron beams

    SciTech Connect

    Garnett, J.L.; Major, G.

    1982-01-01

    The technique of using radiation polymerization for the restoration and preservation of art treasures is considered. The processes discussed include both radiation grafting and rapid cure procedures, particularly reactions initiated by uv and eb. Representative examples where the technique has already been used are treated including typical applications with paintings, tapestries, leather and archival repair. The structure of the monomers and oligomers used in both grafting and rapid cure systems is outlined. The experimental conditions where grafting may occur during radiation rapid cure processing are discussed. Possible future developments of the technique are outlined. 1 figure, 8 tables.

  18. Persistence of endometrial activity after radiation therapy for cervical carcinoma

    SciTech Connect

    Barnhill, D.; Heller, P.; Dames, J.; Hoskins, W.; Gallup, D.; Park, R.

    1985-12-01

    Radiation therapy is a proved treatment for cervical carcinoma; however, it destroys ovarian function and has been thought to ablate the endometrium. Estrogen replacement therapy is often prescribed for patients with cervical carcinoma after radiation therapy. A review of records of six teaching hospitals revealed 16 patients who had endometrial sampling for uterine bleeding after standard radiation therapy for cervical carcinoma. Fifteen patients underwent dilatation and curettage, and one patient underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy when a dilatation and curettage was unsuccessful. Six patients had fibrosis and inflammation of the endometrial cavity, seven had proliferative endometrium, one had cystic hyperplasia, one had atypical adenomatous hyperplasia, and one had adenocarcinoma. Although the number of patients who have an active endometrium after radiation therapy for cervical carcinoma is not known, this report demonstrates that proliferative endometrium may persist, and these patients may develop endometrial hyperplasia or adenocarcinoma. Studies have indicated that patients with normal endometrial glands have an increased risk of developing endometrial adenocarcinoma if they are treated with unopposed estrogen. Patients who have had radiation therapy for cervical carcinoma should be treated with estrogen and a progestational agent to avoid endometrial stimulation from unopposed estrogen therapy.

  19. Detection of uranium enrichment activities using environmental monitoring techniques

    SciTech Connect

    Belew, W.L.; Carter, J.A.; Smith, D.H.; Walker, R.L.

    1993-03-30

    Uranium enrichment processes have the capability of producing weapons-grade material in the form of highly enriched uranium. Thus, detection of undeclared uranium enrichment activities is an international safeguards concern. The uranium separation technologies currently in use employ UF{sub 6} gas as a separation medium, and trace quantities of enriched uranium are inevitably released to the environment from these facilities. The isotopic content of uranium in the vegetation, soil, and water near the plant site will be altered by these releases and can provide a signature for detecting the presence of enriched uranium activities. This paper discusses environmental sampling and analytical procedures that have been used for the detection of uranium enrichment facilities and possible safeguards applications of these techniques.

  20. Pioneering technique using Acellular Dermal Matrix in the rescue of a radiation ulcer

    PubMed Central

    NASEEM, S.; PATEL, A.D.; DEVALIA, H.

    2016-01-01

    Background Radiotherapy as an adjuvant to mastectomy is integral to the treatment of breast cancer, but can result in skin ulceration. Skin ulceration following radiotherapy is traditionally managed by removing the implant and allowing the skin to heal by secondary intention. Case report A 42-year-old woman underwent radiotherapy following a breast reconstruction. She developed a 2 x 3cm radiation ulcer. The ulcer was managed by removing the implant and performing capsulectomy. A Beckers 50 expander was placed and reinforced with acellular dermal matrix inferolaterally. At follow-up the patient had a good cosmetic outcome. Conclusion Post-radiation skin ulcers present a challenge to treat with no current standardised management. The use of acellular dermal matrix may present a new technique to promote healing in these testing cases. PMID:27142826

  1. Evaluation and optimization of the structural parameter of diesel nozzle basing on synchrotron radiation imaging techniques

    NASA Astrophysics Data System (ADS)

    Wu, Z.; Gao, Y.; Gong, H.; Li, L.

    2016-04-01

    Lacking of efficient methods, industry currently uses one only parameter—fuel flow rate—to evaluate the nozzle quality, which is far from satisfying the current emission regulations worldwide. By utilizing synchrotron radiation high energy X-ray in Shanghai Synchrotron Radiation Facility (SSRF), together with the imaging techniques, the 3D models of two nozzles with the same design dimensions were established, and the influence of parameters fluctuation in the azimuthal direction were analyzed in detail. Results indicate that, due to the orifice misalignment, even with the same design dimension, the inlet rounding radius of orifices differs greatly, and its fluctuation in azimuthal direction is also large. This difference will cause variation in the flow characteristics at orifice outlet and then further affect the spray characteristics. The study also indicates that, more precise investigation and insight into the evaluation and optimization of diesel nozzle structural parameter are needed.

  2. An efficient and accurate technique to compute the absorption, emission, and transmission of radiation by the Martian atmosphere

    NASA Technical Reports Server (NTRS)

    Lindner, Bernhard Lee; Ackerman, Thomas P.; Pollack, James B.

    1990-01-01

    CO2 comprises 95 pct. of the composition of the Martian atmosphere. However, the Martian atmosphere also has a high aerosol content. Dust particles vary from less than 0.2 to greater than 3.0. CO2 is an active absorber and emitter in near IR and IR wavelengths; the near IR absorption bands of CO2 provide significant heating of the atmosphere, and the 15 micron band provides rapid cooling. Including both CO2 and aerosol radiative transfer simultaneously in a model is difficult. Aerosol radiative transfer requires a multiple scattering code, while CO2 radiative transfer must deal with complex wavelength structure. As an alternative to the pure atmosphere treatment in most models which causes inaccuracies, a treatment was developed called the exponential sum or k distribution approximation. The chief advantage of the exponential sum approach is that the integration over k space of f(k) can be computed more quickly than the integration of k sub upsilon over frequency. The exponential sum approach is superior to the photon path distribution and emissivity techniques for dusty conditions. This study was the first application of the exponential sum approach to Martian conditions.

  3. Active magnetic radiation shielding system analysis and key technologies.

    PubMed

    Washburn, S A; Blattnig, S R; Singleterry, R C; Westover, S C

    2015-01-01

    Many active magnetic shielding designs have been proposed in order to reduce the radiation exposure received by astronauts on long duration, deep space missions. While these designs are promising, they pose significant engineering challenges. This work presents a survey of the major systems required for such unconfined magnetic field design, allowing the identification of key technologies for future development. Basic mass calculations are developed for each system and are used to determine the resulting galactic cosmic radiation exposure for a generic solenoid design, using a range of magnetic field strength and thickness values, allowing some of the basic characteristics of such a design to be observed. This study focuses on a solenoid shaped, active magnetic shield design; however, many of the principles discussed are applicable regardless of the exact design configuration, particularly the key technologies cited. PMID:26177618

  4. Active magnetic radiation shielding system analysis and key technologies

    NASA Astrophysics Data System (ADS)

    Washburn, S. A.; Blattnig, S. R.; Singleterry, R. C.; Westover, S. C.

    2015-01-01

    Many active magnetic shielding designs have been proposed in order to reduce the radiation exposure received by astronauts on long duration, deep space missions. While these designs are promising, they pose significant engineering challenges. This work presents a survey of the major systems required for such unconfined magnetic field design, allowing the identification of key technologies for future development. Basic mass calculations are developed for each system and are used to determine the resulting galactic cosmic radiation exposure for a generic solenoid design, using a range of magnetic field strength and thickness values, allowing some of the basic characteristics of such a design to be observed. This study focuses on a solenoid shaped, active magnetic shield design; however, many of the principles discussed are applicable regardless of the exact design configuration, particularly the key technologies cited.

  5. MAG4 versus Alternative Techniques for Forecasting Active-Region Flare Productivity

    NASA Astrophysics Data System (ADS)

    Falconer, David; Moore, Ronald L.; Barghouty, Abdulnasser F; Khazanov, Igor

    2014-06-01

    MAG4 is a technique of forecasting an active region's rate of production of major flares in the coming few days from a free-magnetic-energy proxy. We present a statistical method of measuring the difference in performance between MAG4 and comparable alternative techniques that forecast an active region’s major-flare productivity from alternative observed aspects of the active region. We demonstrate the method by measuring the difference in performance between the “Present MAG4” technique and each of three alternative techniques, called “McIntosh Active-Region Class,” “Total Magnetic Flux,” and “Next MAG4.” We do this by using (1) the MAG4 database of magnetograms and major-flare histories of sunspot active regions, (2) the NOAA table of the major-flare productivity of each of 60 McIntosh active-region classes of sunspot active regions, and (3) five technique-performance metrics (Heidke Skill Score, True Skill Score, Percent Correct, Probability of Detection, and False Alarm Rate) evaluated from 2000 random two-by-two contingency tables obtained from the databases. We find that (1) Present MAG4 far outperforms both McIntosh Active-Region Class and Total Magnetic Flux, (2) Next MAG4 significantly outperforms Present MAG4, (3) the performance of Next MAG4 is insensitive to the forward and backward temporal windows used, in the range of one to a few days, and (4) forecasting from the free-energy proxy in combination with either any broad category of McIntosh active-region classes or any Mount Wilson active-region class gives no significant performance improvement over forecasting from the free-energy proxy alone (Present MAG4). Funding for this research came from NASA’s Game Changing Development Program, Johnson Space Center’s Space Radiation Analysis Group (SRAG), and AFOSR’s Multi-University Research Initiative. In particular, funding was facilitated by Dr. Dan Fry (NASA-JSC) and David Moore (NASA-LaRC).

  6. Asymmetric thoracic metaiodobenzylguanidine (MIBG) activity due to prior radiation therapy.

    PubMed

    Bai, Xia; Yang, Hua; Zhuang, Hongming

    2015-06-01

    A 5-year-old patient suffered Horner syndrome, which was caused by a neuroblastoma in the left apex of the lung shown on the initial I-MIBG scan. After the surgical resection and external radiation to the left lung field, a follow-up I-MIBG scan revealed significantly less MIBG activity in the left upper chest compared to the contralateral right upper chest. PMID:25742240

  7. Quantifying reflectance anisotropy of photosynthetically active radiation in grasslands

    NASA Technical Reports Server (NTRS)

    Middleton, Elizabeth M.

    1992-01-01

    Quantifying the vegetative surface's reflectance anisotropy was an important part of the First ISLSCP Field Experiment, as its major objectives focused on retrieval of surface parameters from satellite-derived reflectances. The explicit remote measurements for approximating the bidirectional reflectance distribution function (BRDF) of photosynthetically active radiation had not been previously undertaken. In this paper the proper expression of reflectance for BRDFs for retrieval of canopy parameters is assessed.

  8. Field transients of coherent terahertz synchrotron radiation accessed via time-resolving and correlation techniques

    NASA Astrophysics Data System (ADS)

    Pohl, A.; Semenov, A.; Hübers, H.-W.; Hoehl, A.; Ries, M.; Wüstefeld, G.; Ulm, G.; Ilin, K.; Thoma, P.; Siegel, M.

    2016-03-01

    Decaying oscillations of the electric field in repetitive pulses of coherent synchrotron radiation in the terahertz frequency range was evaluated by means of time-resolving and correlation techniques. Comparative analysis of real-time voltage transients of the electrical response and interferograms, which were obtained with an ultrafast zero-bias Schottky diode detector and a Martin-Puplett interferometer, delivers close values of the pulse duration. Consistent results were obtained via the correlation technique with a pair of Golay Cell detectors and a pair of resonant polarisation-sensitive superconducting detectors integrated on one chip. The duration of terahertz synchrotron pulses does not closely correlate with the duration of single-cycle electric field expected for the varying size of electron bunches. We largely attribute the difference to the charge density oscillations in electron bunches and to the low-frequency spectral cut-off imposed by both the synchrotron beamline and the coupling optics of our detectors.

  9. Thermal radiation characteristics of nonisothermal cylindrical enclosures using a numerical ray tracing technique

    NASA Technical Reports Server (NTRS)

    Baumeister, Joseph F.

    1990-01-01

    Analysis of energy emitted from simple or complex cavity designs can lead to intricate solutions due to nonuniform radiosity and irradiation within a cavity. A numerical ray tracing technique was applied to simulate radiation propagating within and from various cavity designs. To obtain the energy balance relationships between isothermal and nonisothermal cavity surfaces and space, the computer code NEVADA was utilized for its statistical technique applied to numerical ray tracing. The analysis method was validated by comparing results with known theoretical and limiting solutions, and the electrical resistance network method. In general, for nonisothermal cavities the performance (apparent emissivity) is a function of cylinder length-to-diameter ratio, surface emissivity, and cylinder surface temperatures. The extent of nonisothermal conditions in a cylindrical cavity significantly affects the overall cavity performance. Results are presented over a wide range of parametric variables for use as a possible design reference.

  10. Consequences of modern anthropometric dimensions for radiographic techniques and patient radiation exposures

    PubMed Central

    Shah, Chintan; Jones, A. Kyle; Willis, Charles E.

    2008-01-01

    Radiographic techniques are devised on the basis of anatomic dimensions. Inaccurate dimensions can cause radiographs to be exposed inappropriately and patient radiation exposures to be calculated incorrectly. The source of anatomic dimensions in common usage dates back to 1948. The objective of this study was to compare traditional and modern anthropometric data, use modern dimensions to estimate potential errors in patient exposure, and suggest modified technique guidelines. Anthropometry software was used to derive modern anatomic dimensions. Data from routine annual testing were analyzed to develop an x-ray generator output curve. Published tabulated data were used to determine the relationship between tissue half-value layer and kilovoltage. These relationships were used to estimate entrance skin exposure and create a provisional technique guide. While most anatomic regions were actually larger than previously indicated, some were similar, and a few were smaller. Accordingly, exposure estimates were higher, similar, or lower, depending on the anatomic region. Exposure estimates using modern dimensions for clinically significant regions of the trunk were higher than those calculated with traditional dimensions. Exposures of the postero-anterior chest, lateral chest, antero-posterior (AP) abdomen, male AP pelvis, and female AP pelvis were larger by 48%, 31%, 54%, 52%, and 112%, respectively. The dimensions of bony regions of the anatomy, such as the joints and skull, were unchanged. These findings are consistent with the idea that anatomic areas where fat is deposited are larger in the modern U.S. population than they were in previous years. Exposure techniques for manual radiography and calculations of patient dose for automatic exposure control radiography should be adjusted according to the modern dimensions. Population radiation exposure estimates calculated in national surveys should also be modified appropriately. PMID:18777922

  11. An active control strategy for achieving weak radiator structures

    SciTech Connect

    Naghshineh, K. . Acoustics and Radar Technology Lab.); Koopmann, G.H. . Center for Acoustics and Vibration)

    1994-01-01

    A general control strategy is presented for active suppression of total radiated sound power from harmonically excited structures based on the measurement of their response. Using the measured response of the structure together with knowledge of its structural mobility, and equivalent primary excitation force is found at discrete points along the structure. Using this equivalent primary force and performing a quadratic optimization of the power radiated form the structure, a set of control forces is found at selected points on the structure that results in minimum radiated sound power. A numerical example of this strategy is presented for a simply supported beam in a rigid baffle excited by a harmonic plane wave incident at an oblique angle. A comparison of the response of the beam with and without control forces shows a large reduction in the controlled response displacement magnitude. In addition, as the result of the action of the control forces, the magnitude of the wave number spectrum of the beam's response in the supersonic region is decreased substantially. The effect of the number and location of the actuators on reductions in sound power level is also studied. The actuators located at the anti-nodes of structural modes within the supersonic region together with those located near boundaries are found to be the most effective in controlling the radiation of sound from a structure.

  12. Active Extraction of Near-field Thermal Radiation

    NASA Astrophysics Data System (ADS)

    Ding, Ding; Kim, Taeyong; Minnich, Austin

    Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at sub-wavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active radiative cooling (ARC) scheme to extract these modes to the far-field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far-field. We also provide further insights into our ARC scheme by applying the theoretical framework used for laser cooling of solids (LCS) to ARC. We show that LCS and ARC can be described with the same mathematical formalism by replacing the electron-phonon coupling parameter in LCS with the electron-photon coupling parameter in ARC. Using this framework, we examine the predictions of the formalism for LCS and ARC using realistic parameters and find that ARC can achieve higher efficiency and extracted power over a wide range of conditions. Our study demonstrates a new approach to manipulate near-field thermal radiation for thermal management.

  13. International perspectives on quality assurance and new techniques in radiation medicine: outcomes of an IAEA conference.

    PubMed

    Shortt, Ken; Davidsson, Lena; Hendry, Jolyon; Dondi, Maurizio; Andreo, Pedro

    2008-01-01

    The International Atomic Energy Agency organized an international conference called, "Quality Assurance and New Techniques in Radiation Medicine" (QANTRM). It dealt with quality assurance (QA) in all aspects of radiation medicine (diagnostic radiology, nuclear medicine, and radiotherapy) at the international level. Participants discussed QA issues pertaining to the implementation of new technologies and the need for education and staff training. The advantage of developing a comprehensive and harmonized approach to QA covering both the technical and the managerial issues was emphasized to ensure the optimization of benefits to patient safety and effectiveness. The necessary coupling between medical radiation imaging and radiotherapy was stressed, particularly for advanced technologies. However, the need for a more systematic approach to the adoption of advanced technologies was underscored by a report on failures in intensity-modulated radiotherapy dosimetry auditing tests in the United States, which could imply inadequate implementation of QA for these new technologies. A plenary session addressed the socioeconomic impact of introducing advanced technologies in resource-limited settings. How shall the dual gaps, one in access to basic medical services and the other in access to high-quality modern technology, be addressed? PMID:18406944

  14. Numerical analysis of radiation propagation in innovative volumetric receivers based on selective laser melting techniques

    NASA Astrophysics Data System (ADS)

    Alberti, Fabrizio; Santiago, Sergio; Roccabruna, Mattia; Luque, Salvador; Gonzalez-Aguilar, Jose; Crema, Luigi; Romero, Manuel

    2016-05-01

    Volumetric absorbers constitute one of the key elements in order to achieve high thermal conversion efficiencies in concentrating solar power plants. Regardless of the working fluid or thermodynamic cycle employed, design trends towards higher absorber output temperatures are widespread, which lead to the general need of components of high solar absorptance, high conduction within the receiver material, high internal convection, low radiative and convective heat losses and high mechanical durability. In this context, the use of advanced manufacturing techniques, such as selective laser melting, has allowed for the fabrication of intricate geometries that are capable of fulfilling the previous requirements. This paper presents a parametric design and analysis of the optical performance of volumetric absorbers of variable porosity conducted by means of detailed numerical ray tracing simulations. Sections of variable macroscopic porosity along the absorber depth were constructed by the fractal growth of single-cell structures. Measures of performance analyzed include optical reflection losses from the absorber front and rear faces, penetration of radiation inside the absorber volume, and radiation absorption as a function of absorber depth. The effects of engineering design parameters such as absorber length and wall thickness, material reflectance and porosity distribution on the optical performance of absorbers are discussed, and general design guidelines are given.

  15. International Perspectives on Quality Assurance and New Techniques in Radiation Medicine: Outcomes of an IAEA Conference

    SciTech Connect

    Shortt, Ken Davidsson, Lena; Hendry, Jolyon; Dondi, Maurizio; Andreo, Pedro

    2008-05-01

    The International Atomic Energy Agency organized an international conference called, 'Quality Assurance and New Techniques in Radiation Medicine' (QANTRM). It dealt with quality assurance (QA) in all aspects of radiation medicine (diagnostic radiology, nuclear medicine, and radiotherapy) at the international level. Participants discussed QA issues pertaining to the implementation of new technologies and the need for education and staff training. The advantage of developing a comprehensive and harmonized approach to QA covering both the technical and the managerial issues was emphasized to ensure the optimization of benefits to patient safety and effectiveness. The necessary coupling between medical radiation imaging and radiotherapy was stressed, particularly for advanced technologies. However, the need for a more systematic approach to the adoption of advanced technologies was underscored by a report on failures in intensity-modulated radiotherapy dosimetry auditing tests in the United States, which could imply inadequate implementation of QA for these new technologies. A plenary session addressed the socioeconomic impact of introducing advanced technologies in resource-limited settings. How shall the dual gaps, one in access to basic medical services and the other in access to high-quality modern technology, be addressed?.

  16. Initiation techniques and the vacuum-ultraviolet-radiation efficiency of a stabilized multichannel surface discharge

    NASA Astrophysics Data System (ADS)

    Tcheremiskine, V. I.; Uteza, O. P.; Sentis, M. L.; Mikheev, L. D.

    2006-01-01

    Multichannel surface discharges possess a number of advantageous characteristics for the optical pumping of photochemically driven lasers. This work reports on a type of large-area low-inductance sources of intense UV-VUV (vacuum-ultraviolet) radiation based on spatially stabilized multichannel discharges in gases. The discharges consist of several dozens of closely located parallel plasma channels initiated synchronously along a dielectric surface on the area of several hundred square centimeters. In comparison with a large-area diffuse surface discharge, the plasma confinement within relatively thin channels greatly improves the efficiency of the discharge emission in the VUV spectral range. Several techniques are introduced, which allow a synchronous formation and homogeneous development of multiple spatially stabilized discharge channels. Technical efficiency of the discharge radiation within the spectral range of 120-200nm reaches 5% and an effective brightness temperature of the radiating plasma exceeds 20kK. Synchronous operation of a number of multichannel discharge modules producing high-intensity submicrosecond optical pulses is demonstrated, which is of importance for the pump source scaling and geometrical adaptation.

  17. Experimental comparison between speckle and grating-based imaging technique using synchrotron radiation X-rays.

    PubMed

    Kashyap, Yogesh; Wang, Hongchang; Sawhney, Kawal

    2016-08-01

    X-ray phase contrast and dark-field imaging techniques provide important and complementary information that is inaccessible to the conventional absorption contrast imaging. Both grating-based imaging (GBI) and speckle-based imaging (SBI) are able to retrieve multi-modal images using synchrotron as well as lab-based sources. However, no systematic comparison has been made between the two techniques so far. We present an experimental comparison between GBI and SBI techniques with synchrotron radiation X-ray source. Apart from the simple experimental setup, we find SBI does not suffer from the issue of phase unwrapping, which can often be problematic for GBI. In addition, SBI is also superior to GBI since two orthogonal differential phase gradients can be simultaneously extracted by one dimensional scan. The GBI has less stringent requirements for detector pixel size and transverse coherence length when a second or third grating can be used. This study provides the reference for choosing the most suitable technique for diverse imaging applications at synchrotron facility. PMID:27505829

  18. Involved-Node Radiotherapy and Modern Radiation Treatment Techniques in Patients With Hodgkin Lymphoma

    SciTech Connect

    Paumier, Amaury; Ghalibafian, Mithra; Beaudre, Anne; Ferreira, Ivaldo; Pichenot, Charlotte; Messai, Taha; Lessard, Nathalie Athalie; Lefkopoulos, Dimitri; Girinsky, Theodore

    2011-05-01

    Purpose: To assess the clinical outcome of the involved-node radiotherapy (INRT) concept using modern radiation treatments (intensity-modulated radiotherapy [IMRT]or deep-inspiration breath-hold radiotherapy [DIBH) in patients with localized supradiaphragmatic Hodgkin lymphoma. Methods and Materials: All but 2 patients had early-stage Hodgkin lymphoma, and they were treated with chemotherapy prior to irradiation. Radiation treatments were delivered using the INRT concept according to European Organization for Research and Treatment of Cancer guidelines. IMRT was performed with the patient free-breathing. For the adapted breath-hold technique, a spirometer dedicated to DIBH radiotherapy was used. Three-dimensional conformal radiotherapy was performed with those patients. Results: Fifty patients with Hodgkin lymphoma (48 patients with primary Hodgkin lymphoma, 1 patient with recurrent disease, and 1 patient with refractory disease) entered the study from January 2003 to August 2008. Thirty-two patients were treated with IMRT, and 18 patients were treated with the DIBH technique. The median age was 28 years (range, 17-62 years). Thirty-four (68%) patients had stage I - (I-IIA) IIA disease, and 16 (32%) patients had stage I - (I-IIB) IIB disease. All but 3 patients received three to six cycles of adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD). The median radiation doses to patients treated with IMRT and DIBH were, respectively, 40 Gy (range, 21.6-40 Gy) and 30.6 Gy (range, 19.8-40 Gy). Protection of various organs at risk was satisfactory. Median follow-up was 53.4 months (range, 19.1-93 months). The 5-year progression-free and overall survival rates for the whole population were 92% (95% confidence interval [CI], 80%-97%) and 94% (95% CI, 75%-98%), respectively. Recurrences occurred in 4 patients: 2 patients had in-field relapses, and 2 patients had visceral recurrences. Grade 3 acute lung toxicity (transient pneumonitis) occurred in 1 case. Conclusions

  19. Active control technique of fractional-order chaotic complex systems

    NASA Astrophysics Data System (ADS)

    Mahmoud, Gamal M.; Ahmed, Mansour E.; Abed-Elhameed, Tarek M.

    2016-06-01

    Several kinds of synchronization of fractional-order chaotic complex systems are challenging research topics of current interest since they appear in many applications in applied sciences. Our main goal in this paper is to introduce the definition of modified projective combination-combination synchronization (MPCCS) of some fractional-order chaotic complex systems. We show that our systems are chaotic by calculating their Lyapunov exponents. The fractional Lyapunov dimension of the chaotic solutions of these systems is computed. A scheme is introduced to calculate MPCCS of four different (or identical) chaotic complex systems using the active control technique. Special cases of this type, which are projective and anti C-C synchronization, are discussed. Some figures are plotted to show that MPCCS is achieved and its errors approach zero.

  20. Activation studies of NEG coatings by surface techniques

    SciTech Connect

    Sharma, R. K.; Jagannath,; Bhushan, K. G.; Gadkari, S. C.; Mukund, R.; Gupta, S. K.

    2013-02-05

    NEG (Non Evaporable Getters)materials in the form of ternary alloy coatings have many benefits compare to traditional bare surfaces such as Extreme high vacuum(XHV), lower secondary electron yield(SEY), low photon desorption cofficient. The extreme high vacuum (pressure > 10{sup -10} mbar) is very useful to the study of surfaces of the material, for high energy particle accelerators(LHC, Photon Factories), synchrotrons (ESRF, Ellectra) etc. Low secondary electron yield leads to better beam life time. In LHC the pressure in the interaction region of the two beams is something of the order of 10{sup -12} mbar. In this paper preparation of the coatings and their characterization to get the Activation temperature by using the surface techniques XPS, SEM and SIMS has been shown.

  1. Active Learning Techniques Applied to an Interdisciplinary Mineral Resources Course.

    NASA Astrophysics Data System (ADS)

    Aird, H. M.

    2015-12-01

    An interdisciplinary active learning course was introduced at the University of Puget Sound entitled 'Mineral Resources and the Environment'. Various formative assessment and active learning techniques that have been effective in other courses were adapted and implemented to improve student learning, increase retention and broaden knowledge and understanding of course material. This was an elective course targeted towards upper-level undergraduate geology and environmental majors. The course provided an introduction to the mineral resources industry, discussing geological, environmental, societal and economic aspects, legislation and the processes involved in exploration, extraction, processing, reclamation/remediation and recycling of products. Lectures and associated weekly labs were linked in subject matter; relevant readings from the recent scientific literature were assigned and discussed in the second lecture of the week. Peer-based learning was facilitated through weekly reading assignments with peer-led discussions and through group research projects, in addition to in-class exercises such as debates. Writing and research skills were developed through student groups designing, carrying out and reporting on their own semester-long research projects around the lasting effects of the historical Ruston Smelter on the biology and water systems of Tacoma. The writing of their mini grant proposals and final project reports was carried out in stages to allow for feedback before the deadline. Speakers from industry were invited to share their specialist knowledge as guest lecturers, and students were encouraged to interact with them, with a view to employment opportunities. Formative assessment techniques included jigsaw exercises, gallery walks, placemat surveys, think pair share and take-home point summaries. Summative assessment included discussion leadership, exams, homeworks, group projects, in-class exercises, field trips, and pre-discussion reading exercises

  2. Measuring the activity of a {sup 51}Cr neutrino source based on the gamma-radiation spectrum

    SciTech Connect

    Gorbachev, V. V. Gavrin, V. N.; Ibragimova, T. V.; Kalikhov, A. V.; Malyshkin, Yu. M.; Shikhin, A. A.

    2015-12-15

    A technique for the measurement of activities of intense β sources by measuring the continuous gamma-radiation (internal bremsstrahlung) spectra is developed. A method for reconstructing the spectrum recorded by a germanium semiconductor detector is described. A method for the absolute measurement of the internal bremsstrahlung spectrum of {sup 51}Cr is presented.

  3. Activating PTEN by COX-2 inhibitors antagonizes radiation-induced AKT activation contributing to radiosensitization.

    PubMed

    Meng, Zhen; Gan, Ye-Hua

    2015-05-01

    Radiotherapy is still one of the most effective nonsurgical treatments for many tumors. However, radioresistance remains a major impediment to radiotherapy. Although COX-2 inhibitors can induce radiosensitization, the underlying mechanism is not fully understood. In this study, we showed that COX-2 selective inhibitor celecoxib enhanced the radiation-induced inhibition of cell proliferation and apoptosis in HeLa and SACC-83 cells. Treatment with celecoxib alone dephosphorylated phosphatase and tensin homolog deleted on chromosome ten (PTEN), promoted PTEN membrane translocation or activation, and correspondingly dephosphorylated or inactivated protein kinase B (AKT). By contrast, treatment with radiation alone increased PTEN phosphorylation, inhibited PTEN membrane translocation and correspondingly activated AKT in the two cell lines. However, treatment with celecoxib or another COX-2 selective inhibitor (valdecoxib) completely blocked radiation-induced increase of PTEN phosphorylation, rescued radiation-induced decrease in PTEN membrane translocation, and correspondingly inactivated AKT. Moreover, celecoxib could also upregulate PTEN protein expression by downregulating Sp1 expression, thereby leading to the activation of PTEN transcription. Our results suggested that COX-2 inhibitors could enhance radiosensitization at least partially by activating PTEN to antagonize radiation-induced AKT activation. PMID:25770423

  4. Radiation treatment for the right naris in a pediatric anesthesia patient using an adaptive oral airway technique

    SciTech Connect

    Sponseller, Patricia Pelly, Nicole; Trister, Andrew; Ford, Eric; Ermoian, Ralph

    2015-10-01

    Radiation therapy for pediatric patients often includes the use of intravenous anesthesia with supplemental oxygen delivered via the nasal cannula. Here, we describe the use of an adaptive anesthesia technique for electron irradiation of the right naris in a preschool-aged patient treated under anesthesia. The need for an intranasal bolus plug precluded the use of standard oxygen supplementation. This novel technique required the multidisciplinary expertise of anesthesiologists, radiation therapists, medical dosimetrists, medical physicists, and radiation oncologists to ensure a safe and reproducible treatment course.

  5. Larynx-sparing techniques using intensity-modulated radiation therapy for oropharyngeal cancer

    SciTech Connect

    Bar Ad, Voichita; Lin, Haibo; Hwang, Wei-Ting; Deville, Curtiland; Dutta, Pinaki R.; Tochner, Zelig; Both, Stefan

    2012-01-01

    The purpose of the current study was to explore whether the laryngeal dose can be reduced by using 2 intensity-modulated radiation therapy (IMRT) techniques: whole-neck field IMRT technique (WF-IMRT) vs. junctioned IMRT (J-IMRT). The effect on planning target volumes (PTVs) coverage and laryngeal sparing was evaluated. WF-IMRT technique consisted of a single IMRT plan, including the primary tumor and the superior and inferior neck to the level of the clavicular heads. The larynx was defined as an organ at risk extending superiorly to cover the arytenoid cartilages and inferiorly to include the cricoid cartilage. The J-IMRT technique consisted of an IMRT plan for the primary tumor and the superior neck, matched to conventional antero-posterior opposing lower neck fields at the level of the thyroid notch. A central block was used for the anterior lower neck field at the level of the larynx to restrict the dose to the larynx. Ten oropharyngeal cancer cases were analyzed. Both the primary site and bilateral regional lymphatics were included in the radiotherapy targets. The averaged V95 for the PTV57.6 was 99.2% for the WF-IMRT technique compared with 97.4% (p = 0.02) for J-IMRT. The averaged V95 for the PTV64 was 99.9% for the WF-IMRT technique compared with 98.9% (p = 0.02) for J-IMRT and the averaged V95 for the PT70 was 100.0% for WF-IMRT technique compared with 99.5% (p = 0.04) for J-IMRT. The averaged mean laryngeal dose was 18 Gy with both techniques. The averaged mean doses within the matchline volumes were 69.3 Gy for WF-MRT and 66.2 Gy for J-IMRT (p = 0.03). The WF-IMRT technique appears to offer an optimal coverage of the target volumes and a mean dose to the larynx similar with J-IMRT and should be further evaluated in clinical trials.

  6. Simplified field-in-field technique for a large-scale implementation in breast radiation treatment

    SciTech Connect

    Fournier-Bidoz, Nathalie; Kirova, Youlia M.; Campana, Francois; Dendale, Remi; Fourquet, Alain

    2012-07-01

    We wanted to evaluate a simplified 'field-in-field' technique (SFF) that was implemented in our department of Radiation Oncology for breast treatment. This study evaluated 15 consecutive patients treated with a simplified field in field technique after breast-conserving surgery for early-stage breast cancer. Radiotherapy consisted of whole-breast irradiation to the total dose of 50 Gy in 25 fractions, and a boost of 16 Gy in 8 fractions to the tumor bed. We compared dosimetric outcomes of SFF to state-of-the-art electronic surface compensation (ESC) with dynamic leaves. An analysis of early skin toxicity of a population of 15 patients was performed. The median volume receiving at least 95% of the prescribed dose was 763 mL (range, 347-1472) for SFF vs. 779 mL (range, 349-1494) for ESC. The median residual 107% isodose was 0.1 mL (range, 0-63) for SFF and 1.9 mL (range, 0-57) for ESC. Monitor units were on average 25% higher in ESC plans compared with SFF. No patient treated with SFF had acute side effects superior to grade 1-NCI scale. SFF created homogenous 3D dose distributions equivalent to electronic surface compensation with dynamic leaves. It allowed the integration of a forward planned concomitant tumor bed boost as an additional multileaf collimator subfield of the tangential fields. Compared with electronic surface compensation with dynamic leaves, shorter treatment times allowed better radiation protection to the patient. Low-grade acute toxicity evaluated weekly during treatment and 2 months after treatment completion justified the pursuit of this technique for all breast patients in our department.

  7. MBI facility at BESSY II for time-resolved pump-probe techniques with laser and undulator radiation

    NASA Astrophysics Data System (ADS)

    Gatzke, Johannes; Winter, Bernd J.; Quast, T.; Hertel, Ingolf V.

    1998-10-01

    The MBI develops a facility at BESSY II dedicated to pump- probe techniques combining synchrotron and laser radiation. The synchronization of laser and synchrotron pulses will allow time resolved experiments on the picosecond time scale at this. The features of the facility, the optical parameters of the synchrotron beamline, the synchronization technique and pulse stretching considerations will be outlined. Current developments will be reported.

  8. Radiation Dose Reduction in Transmission CT Using a Novel Iterative Fourier-Based Reconstruction Technique

    NASA Astrophysics Data System (ADS)

    Fahimian, Benjamin Pooya

    Tomographic imaging has had a radical impact on diverse fields ranging from the study of the small in microscopy, to the study of the large in astronomy, but perhaps most significantly, it has unequivocally revolutionized the practice of medicine. Although the applications of tomography are wide and diverse, the central problems associated with its mathematical and experimental implementation are similar. Most notably, the problem of image reconstruction from missing and noisy projection data and the problem of radiation dose imparted to biological specimens and patients are persistent and prominent problems in tomographic applications. Since by virtue of its nature, tomographic reconstruction is a mathematical problem, the development of more accurate and sophisticated reconstruction algorithms capable of solving for missing projection data and or producing accurate lower noise reconstructions, may hold promise in alleviating such problems. In this work, a method of tomographic acquisition and exact iterative Fourier-based reconstruction is developed, which in conjunction with physical constraints, advanced regularization constraints, and an oversampling method, aims to solve for the missing projection data and arrive at a less noisy solution in a manner that is concurrently and strictly consistent with the experimental data. Specifically, the proposed technique, termed Equally-Sloped Tomography (EST), is experimentally implemented and evaluated on four important transmission tomographic imaging modalities: transmission electron microtomography, synchrotron x-ray phase contrast tomography, synchrotron x-ray absorption tomography, and kilovoltage x-ray medical CT. In each modality, using a series of image quality phantoms studies, the performance of technique is quantitatively assessed and compared to existing methods. The potential for dose reduction is investigated by determining the factor by which the number of projections or the source flux can be reduced

  9. Radiation does from medical in-vivo prompt gamma-ray activation using a mobile nuclear reactor.

    PubMed

    Chung, C; Chen, C P; Chang, P S

    1988-10-01

    A method of medical diagnosis of toxic elements, using a neutron beam from a mobile nuclear reactor to perform partial-body in-vivo prompt gamma-ray activation technique, has been developed. Both neutron and gamma-ray dose equivalents in an irradiated phantom and around medical researchers were measured and evaluated. Neutron flux at various kinetic energies was measured using an activation foil technique, and the neutron dose equivalents at tissues of risk inside the irradiated phantom were calculated by neutron transport code. Gamma-ray dose equivalents inside the irradiated phantom and around the nuclear reactor were measured by thermoluminescent dosimeters. The risk associated with the neutron and gamma radiation dose equivalents received by both the irradiated phantom and medical researchers were evaluated in detail. The radiation safety of the in-vivo medical diagnosis using the mobile nuclear reactor, under the context of radiation protection guidelines, is discussed. PMID:3170218

  10. Study of novel techniques for verification imaging and patient dose reconstruction in external beam radiation therapy

    NASA Astrophysics Data System (ADS)

    Jarry, Genevieve

    Treatment delivery verification is an essential step of radiotherapy. The purpose of this thesis is to develop new methods to improve the verification of photon and electron beam radiotherapy treatments. This is achieved through developing and testing (1) a way to acquire portal images during electron beam treatments, (2) a method to reconstruct the dose delivered to patients during photon beam treatments and (3) a technique to improve image quality in kilovoltage (kV) cone beam computed tomography (CBCT) by correcting for scattered radiation. The portal images were acquired using the Varian CL21EX linac and the Varian aS500 electronic portal imaging device (EPID). The EGSnrc code was used to model fully the CL21EX, the aS500 and the kV CBCT system. We demonstrate that portal images of electron beam treatments with adequate contrast and resolution can be produced using the bremsstrahlung photons portion of the electron beam. Monte Carlo (MC) calculations were used to characterize the bremsstrahlung photons and to obtain predicted images of various phantoms. The technique was applied on a head and neck patient. An algorithm to reconstruct the dose given to patients during photon beam radiotherapy was developed and validated. The algorithm uses portal images and MC simulations. The primary fluence at the detector is back-projected through the patient. CT geometry to obtain a reconstructed phase space file. The reconstructed phase space file is used to calculate the reconstructed dose to the patient using MC simulations. The reconstruction method was validated in homogeneous and heterogeneous phantoms for conventional and IMRT fields. The scattered radiation present in kV CBCT images was evaluated using MC simulations. Simulated predictions of the scatter distribution were subtracted from CBCT projection images prior to the reconstruction to improve the reconstructed image quality. Reducing the scattered radiation was found to improve contrast and reduce shading

  11. Stanford Synchrotron Radiation Laboratory activity report for 1987

    SciTech Connect

    Robinson, S.; Cantwell, K.

    1988-12-31

    During 1987, SSRL achieved many significant advances and reached several major milestones utilizing both SPEAR and PEP as synchrotron radiation sources as described in this report. Perhaps the following two are worthy of particular mention: (1) SPEAR reached an all time high of 4,190 delivered user-shifts during calendar year 1987, highlights of the many scientific results are given; (2) during a 12 day run in December of 1987, PEP was operated in a low emittance mode (calculated emittance 6.4 nanometer-radians) at 7.1 GeV with currents up to 33 mA. A second undulator beam line on PEP was commissioned during this run and used to record many spectra showing the extremely high brightness of the radiation. PEP is now by far the highest brightness synchrotron radiation source in the world. The report is divided into the following sections: (1) laboratory operations; (2) accelerator physics programs; (3) experimental facilities; (4) engineering division; (5) conferences and workshops; (6) SSRL organization; (7) experimental progress reports; (8) active proposals; (9) SSRL experiments and proposals by institution; and (10) SSRL publications.

  12. Activation of Protease Activated Receptor 2 by Exogenous Agonist Exacerbates Early Radiation Injury in Rat Intestine

    SciTech Connect

    Wang Junru; Boerma, Marjan; Kulkarni, Ashwini; Hollenberg, Morley D.; Hauer-Jensen, Martin

    2010-07-15

    Purpose: Protease-activated receptor-2 (PAR{sub 2}) is highly expressed throughout the gut and regulates the inflammatory, mitogenic, fibroproliferative, and nociceptive responses to injury. PAR{sub 2} is strikingly upregulated and exhibits increased activation in response to intestinal irradiation. We examined the mechanistic significance of radiation enteropathy development by assessing the effect of exogenous PAR{sub 2} activation. Methods and Materials: Rat small bowel was exposed to localized single-dose radiation (16.5 Gy). The PAR{sub 2} agonist (2-furoyl-LIGRLO-NH{sub 2}) or vehicle was injected intraperitoneally daily for 3 days before irradiation (before), for 7 days after irradiation (after), or both 3 days before and 7 days after irradiation (before-after). Early and delayed radiation enteropathy was assessed at 2 and 26 weeks after irradiation using quantitative histologic examination, morphometry, and immunohistochemical analysis. Results: The PAR{sub 2} agonist did not elicit changes in the unirradiated (shielded) intestine. In contrast, in the irradiated intestine procured 2 weeks after irradiation, administration of the PAR{sub 2} agonist was associated with more severe mucosal injury and increased intestinal wall thickness in all three treatment groups (p <.05) compared with the vehicle-treated controls. The PAR{sub 2} agonist also exacerbated the radiation injury score, serosal thickening, and mucosal inflammation (p <.05) in the before and before-after groups. The short-term exogenous activation of PAR{sub 2} did not affect radiation-induced intestinal injury at 26 weeks. Conclusion: The results of the present study support a role for PAR{sub 2} activation in the pathogenesis of early radiation-induced intestinal injury. Pharmacologic PAR{sub 2} antagonists might have the potential to reduce the intestinal side effects of radiotherapy and/or as countermeasures in radiologic accidents or terrorism scenarios.

  13. Active sampling technique to enhance chemical signature of buried explosives

    NASA Astrophysics Data System (ADS)

    Lovell, John S.; French, Patrick D.

    2004-09-01

    Deminers and dismounted countermine engineers commonly use metal detectors, ground penetrating radar and probes to locate mines. Many modern landmines have a very low metal content, which severely limits the effectiveness of metal detectors. Canines have also been used for landmine detection for decades. Experiments have shown that canines smell the explosives which are known to leak from most types of landmines. The fact that dogs can detect landmines indicates that vapor sensing is a viable approach to landmine detection. Several groups are currently developing systems to detect landmines by "sniffing" for the ultra-trace explosive vapors above the soil. The amount of material that is available to passive vapor sensing systems is limited to no more than the vapor in equilibrium with the explosive related chemicals (ERCs) distributed in the surface soils over and near the landmine. The low equilibrium vapor pressure of TNT in the soil/atmosphere boundary layer and the limited volume of the boundary layer air imply that passive chemical vapor sensing systems require sensitivities in the picogram range, or lower. ADA is working to overcome many of the limitations of passive sampling methods, by the use of an active sampling method that employs a high-powered (1,200+ joules) strobe lamp to create a highly amplified plume of vapor and/or ERC-bearing fine particulates. Initial investigations have demonstrated that this approach can amplify the detectability of TNT by two or three orders of magnitude. This new active sampling technique could be used with any suitable explosive sensor.

  14. Improved mesh based photon sampling techniques for neutron activation analysis

    SciTech Connect

    Relson, E.; Wilson, P. P. H.; Biondo, E. D.

    2013-07-01

    The design of fusion power systems requires analysis of neutron activation of large, complex volumes, and the resulting particles emitted from these volumes. Structured mesh-based discretization of these problems allows for improved modeling in these activation analysis problems. Finer discretization of these problems results in large computational costs, which drives the investigation of more efficient methods. Within an ad hoc subroutine of the Monte Carlo transport code MCNP, we implement sampling of voxels and photon energies for volumetric sources using the alias method. The alias method enables efficient sampling of a discrete probability distribution, and operates in 0(1) time, whereas the simpler direct discrete method requires 0(log(n)) time. By using the alias method, voxel sampling becomes a viable alternative to sampling space with the 0(1) approach of uniformly sampling the problem volume. Additionally, with voxel sampling it is straightforward to introduce biasing of volumetric sources, and we implement this biasing of voxels as an additional variance reduction technique that can be applied. We verify our implementation and compare the alias method, with and without biasing, to direct discrete sampling of voxels, and to uniform sampling. We study the behavior of source biasing in a second set of tests and find trends between improvements and source shape, material, and material density. Overall, however, the magnitude of improvements from source biasing appears to be limited. Future work will benefit from the implementation of efficient voxel sampling - particularly with conformal unstructured meshes where the uniform sampling approach cannot be applied. (authors)

  15. Radiation-based techniques for use in the border protection context

    NASA Astrophysics Data System (ADS)

    Creagh, Dudley

    2014-02-01

    Most airline travelers will be familiar with the current overt passenger examination procedures: metal detectors and small tunnel X-ray examination systems. The mix of overt and covert systems used to prevent dangerous goods and contraband from passing through the portal is constantly changing, dictated by policy decisions made by governments. The United States of America and the European Union are the largest regulatory bodies, and their procedures are adopted by smaller countries: Australia, for example.This paper discusses a wide variety of techniques used by Border Protection Agencies. Most of these examination systems involve the use of the emission, absorption, and scattering of electromagnetic radiation and descriptions of these systems will comprise the bulk of this paper.However, a brief discussion of the use of neutron scattering will be given to demonstrate how systems for the examination of large objects may develop in the future.

  16. Second primary cancers after radiation for prostate cancer: A systematic review of the clinical data and impact of treatment technique

    PubMed Central

    Murray, Louise; Henry, Ann; Hoskin, Peter; Siebert, Frank-Andre; Venselaar, Jack

    2014-01-01

    The development of a radiation induced second primary cancer (SPC) is one the most serious long term consequences of successful cancer treatment. This review aims to evaluate SPC in prostate cancer (PCa) patients treated with radiotherapy, and assess whether radiation technique influences SPC. A systematic review of the literature was performed to identify studies examining SPC in irradiated PCa patients. This identified 19 registry publications, 21 institutional series and 7 other studies. There is marked heterogeneity in published studies. An increased risk of radiation-induced SPC has been identified in several studies, particularly those with longer durations of follow-up. The risk of radiation-induced SPC appears small, in the range of 1 in 220 to 1 in 290 over all durations of follow-up, and may increase to 1 in 70 for patients followed up for more than 10 years, based on studies which include patients treated with older radiation techniques (i.e. non-conformal, large field). To date there are insufficient clinical data to draw firm conclusions about the impact of more modern techniques such as IMRT and brachytherapy on SPC risk, although limited evidence is encouraging. In conclusion, despite heterogeneity between studies, an increased risk of SPC following radiation for PCa has been identified in several studies, and this risk appears to increase over time. This must be borne in mind when considering which patients to irradiate and which techniques to employ. PMID:24485765

  17. Novel Technique for Hepatic Fiducial Marker Placement for Stereotactic Body Radiation Therapy

    SciTech Connect

    Jarraya, Hajer; Chalayer, Chloé; Tresch, Emmanuelle; Bonodeau, Francois; Lacornerie, Thomas; Mirabel, Xavier; Boulanger, Thomas; Taieb, Sophie; Kramar, Andrew; Lartigau, Eric; Ceugnart, Luc

    2014-09-01

    Purpose: To report experience with fiducial marker insertion and describe an advantageous, novel technique for fiducial placement in the liver for stereotactic body radiation therapy with respiratory tracking. Methods and Materials: We implanted 1444 fiducials (single: 834; linked: 610) in 328 patients with 424 hepatic lesions. Two methods of implantation were compared: the standard method (631 single fiducials) performed on 153 patients from May 2007 to May 2010, and the cube method (813 fiducials: 610 linked/203 single) applied to 175 patients from April 2010 to March 2013. The standard method involved implanting a single marker at a time. The novel technique entailed implanting 2 pairs of linked markers when possible in a way to occupy the perpendicular edges of a cube containing the tumor inside. Results: Mean duration of the cube method was shorter than the standard method (46 vs 61 minutes; P<.0001). Median numbers of skin and subcapsular entries were significantly smaller with the cube method (2 vs 4, P<.0001, and 2 vs 4, P<.0001, respectively). The rate of overall complications (total, major, and minor) was significantly lower in the cube method group compared with the standard method group (5.7% vs 13.7%; P=.013). Major complications occurred while using single markers only. The success rate was 98.9% for the cube method and 99.3% for the standard method. Conclusions: We propose a new technique of hepatic fiducial implantation that makes use of linked fiducials and involves fewer skin entries and shorter time of implantation. The technique is less complication-prone and is migration-resistant.

  18. Lab-Based Measurement of Remediation Techniques for Radiation Portal Monitors (Initial Report)

    SciTech Connect

    Livesay, Jake; Guzzardo, Tyler; Lousteau, Angela L

    2012-02-01

    Radiation Portal Monitors (RPM) deployed by the Second Line of Defense (SLD) are known to be sensitive to the natural environmental radioactive background. There are several techniques used to mitigate the effects of background on the monitors, but since the installation environments can vary significantly from one another the need for a standardized, systematic, study of remediation techniques was proposed and carried out. This study is not meant to serve as the absolute last word on the subject. The data collected are, however, intelligible and useful. Some compromises were made, each of which will be described in detail. The hope of this initial report is to familiarize the SLD science teams with ORNL's effort to model the effect of various remediation techniques on simple, static backgrounds. This study provides a good start toward benchmarking the model, and each additional increment of data will serve to make the model more robust. The scope of this initial study is limited to a few basic cases. Its purpose is to prove the utility of lab-based study of remediation techniques and serve as a standard data set for future use. This importance of this first step of standardization will become obvious when science teams are working in parallel on issues of remediation; having a common starting point will do away with one category of difference, thereby making easier the task of determining the sources of disagreement. Further measurements will augment this data set, allowing for further constraint of the universe of possible situations. As will be discussed in the 'Going Forward' section, more data will be included in the final report of this work. Of particular interest will be the data taken with the official TSA lead collimators, which will provide more direct results for comparison with installation data.

  19. Chirp excitation technique to enhance microbubble displacement induced by ultrasound radiation force.

    PubMed

    Hu, Yi; Zhang, Dong; Zheng, Hairong; Gong, Xiufen

    2009-03-01

    Ultrasound radiation force has been proposed to increase the targeting efficiency in ultrasonic molecular imaging and drug delivery. A chirp excitation technique is proposed to increase the radiation force induced microbubble displacement and might potentially be used for enhancing the targeting efficiency of microbubble clouds. In this study, a modified Rayleigh-Plesset equation is used to estimate the radius-time behavior of insonified microbubbles, and the translation of insonified microbubbles is calculated by using the particle trajectory equation. Simulations demonstrate that the chirp excitation is superior to the sinusoidal one in displacing microbubbles with a wide-size distribution, and that the performance is dependent on the parameters of the chirp signal such as the center frequency and frequency range. For Gaussian size distributed microbubble clouds with mean diameter of 3.5 microm and variance of 1, a 2.25 MHz chirp with frequency range of 1.5 MHz induces about 59.59% more microbubbles over a distance of 10 microm during 200 micros insonification, compared to a 2.25 MHz sinusoidal excitation with equal acoustic pressure. PMID:19275298

  20. Preparation of Poly Acrylic Acid-Poly Acrylamide Composite Nanogels by Radiation Technique

    PubMed Central

    Ghorbaniazar, Parisa; Sepehrianazar, Amir; Eskandani, Morteza; Nabi-Meibodi, Mohsen; Kouhsoltani, Maryam; Hamishehkar, Hamed

    2015-01-01

    Purpose: Nanogel, a nanoparticle prepared from a cross-linked hydrophilic polymer network, has many biomedical applications. A radiation technique has recently been introduced as one of the appropriate methods for the preparation of polymeric nanogels due to its additive-free initiation and easy control procedure. Methods: We have investigated the formation of nano-sized polymeric gels, based on the radiation-induced inter- and intra-molecular cross-linking of the inter-polymer complex (IPC) of polyacrylamide (PAAm) and polyacrylic acide (PAAc). Results: The results indicated that the prepared polymeric complex composed of PAAm and PAAc was converted into nanogel by irradiation under different doses (1, 3, 5 and 7 kGy). This was due to inter- and intra-molecular cross-linking at the range of 446-930 nm as characterized by the photon correlation spectroscopy method. Increasing the irradiation dose reduced the size of nanoparticles to 3 kGy; however, the higher doses increased the size and size distribution. Scanning electron microscopy images indicated the nanogel formation in the reported size by particle size and showed the microcapsule structure of the prepared nanogels. Biocompatibility of nanogels were assessed and proved by MTT assay. Conclusion: It was concluded that low dose irradiation can be successfully applied for nanometre-ranged hydrogel. PMID:26236667

  1. The virtual microphone technique in active sound field control systems

    NASA Astrophysics Data System (ADS)

    Lampropoulos, Iraklis E.; Shimizu, Yasushi

    2003-04-01

    Active Sound Field Control (AFC) has been proven very useful in reverberation enhancement applications in large rooms. However, feedback control is required in order to eliminate peaks in the frequency response of the system. The present research closely follows the studies of Shimizu in AFC, in which smoothing of the rooms transfer function is achieved by averaging the impulse responses of multiple microphones. ``The virtual or rotating microphone technique'' reduces the number of microphones in the aforementioned AFC technology, while still achieving the same acoustical effects in the room. After the impulse responses at previously specified pairs of microphone positions are measured, the ratio of transfer functions for every pair is calculated, thus yielding a constant K. Next, microphones are removed and their impulse responses are reproduced by processing the incoming signal of each pair through a convolver, where the computed K constants have been previously stored. Band limiting, windowing and time variance effects are critical factors, in order to reduce incoherence effects and yield reliable approximations of inverse filters and consequently calculations of K. The project is implemented in a church lacking low frequency reverberation for music and makes use of 2 physical and 2 virtual microphones.

  2. Residual matrix from different separation techniques impacts exosome biological activity

    PubMed Central

    Paolini, Lucia; Zendrini, Andrea; Noto, Giuseppe Di; Busatto, Sara; Lottini, Elisabetta; Radeghieri, Annalisa; Dossi, Alessandra; Caneschi, Andrea; Ricotta, Doris; Bergese, Paolo

    2016-01-01

    Exosomes are gaining a prominent role in research due to their intriguing biology and several therapeutic opportunities. However, their accurate purification from body fluids and detailed physicochemical characterization remain open issues. We isolated exosomes from serum of patients with Multiple Myeloma by four of the most popular purification methods and assessed the presence of residual contaminants in the preparations through an ad hoc combination of biochemical and biophysical techniques - including Western Blot, colloidal nanoplasmonics, atomic force microscopy (AFM) and scanning helium ion microscopy (HIM). The preparations obtained by iodixanol and sucrose gradients were highly pure. To the contrary, those achieved with limited processing (serial centrifugation or one step precipitation kit) resulted contaminated by a residual matrix, embedding the exosomes. The contaminated preparations showed lower ability to induce NfkB nuclear translocation in endothelial cells with respect to the pure ones, probably because the matrix prevents the interaction and fusion of the exosomes with the cell membrane. These findings suggest that exosome preparation purity must be carefully assessed since it may interfere with exosome biological activity. Contaminants can be reliably probed only by an integrated characterization approach aimed at both the molecular and the colloidal length scales. PMID:27009329

  3. A snapshot of radiation therapy techniques and technology in Queensland: An aid to mapping undergraduate curriculum

    SciTech Connect

    Bridge, Pete; Carmichael, Mary-Ann; Brady, Carole; Dry, Allison

    2013-03-15

    Undergraduate students studying the Bachelor of Radiation Therapy at Queensland University of Technology (QUT) attend clinical placements in a number of department sites across Queensland. To ensure that the curriculum prepares students for the most common treatments and current techniques in use in these departments, a curriculum matching exercise was performed. A cross-sectional census was performed on a pre-determined “Snapshot” date in 2012. This was undertaken by the clinical education staff in each department who used a standardized proforma to count the number of patients as well as prescription, equipment, and technique data for a list of tumour site categories. This information was combined into aggregate anonymized data. All 12 Queensland radiation therapy clinical sites participated in the Snapshot data collection exercise to produce a comprehensive overview of clinical practice on the chosen day. A total of 59 different tumour sites were treated on the chosen day and as expected the most common treatment sites were prostate and breast, comprising 46% of patients treated. Data analysis also indicated that intensity-modulated radiotherapy (IMRT) use is relatively high with 19.6% of patients receiving IMRT treatment on the chosen day. Both IMRT and image-guided radiotherapy (IGRT) indications matched recommendations from the evidence. The Snapshot method proved to be a feasible and efficient method of gathering useful data to inform curriculum matching. Frequency of IMRT use in Queensland matches or possibly exceeds that indicated in the literature. It is recommended that future repetition of the study be undertaken in order to monitor trends in referral patterns and new technology implementation.

  4. A snapshot of radiation therapy techniques and technology in Queensland: An aid to mapping undergraduate curriculum

    PubMed Central

    Bridge, Pete; Carmichael, Mary-Ann; Brady, Carole; Dry, Allison

    2013-01-01

    Introduction Undergraduate students studying the Bachelor of Radiation Therapy at Queensland University of Technology (QUT) attend clinical placements in a number of department sites across Queensland. To ensure that the curriculum prepares students for the most common treatments and current techniques in use in these departments, a curriculum matching exercise was performed. Methods A cross-sectional census was performed on a pre-determined “Snapshot” date in 2012. This was undertaken by the clinical education staff in each department who used a standardized proforma to count the number of patients as well as prescription, equipment, and technique data for a list of tumour site categories. This information was combined into aggregate anonymized data. Results All 12 Queensland radiation therapy clinical sites participated in the Snapshot data collection exercise to produce a comprehensive overview of clinical practice on the chosen day. A total of 59 different tumour sites were treated on the chosen day and as expected the most common treatment sites were prostate and breast, comprising 46% of patients treated. Data analysis also indicated that intensity-modulated radiotherapy (IMRT) use is relatively high with 19.6% of patients receiving IMRT treatment on the chosen day. Both IMRT and image-guided radiotherapy (IGRT) indications matched recommendations from the evidence. Conclusion The Snapshot method proved to be a feasible and efficient method of gathering useful data to inform curriculum matching. Frequency of IMRT use in Queensland matches or possibly exceeds that indicated in the literature. It is recommended that future repetition of the study be undertaken in order to monitor trends in referral patterns and new technology implementation. PMID:26229604

  5. Double side read-out technique for mitigation of radiation damage effects in PbWO4 crystals

    NASA Astrophysics Data System (ADS)

    Lucchini, M. T.; Auffray, E.; Benaglia, A.; Cavallari, F.; Cockerill, D.; Dolgopolov, A.; Faure, J. L.; Golubev, N.; Hobson, P. R.; Jain, S.; Korjik, M.; Mechinski, V.; Singovski, A.; Tabarelli de Fatis, T.; Tarasov, I.; Zahid, S.

    2016-04-01

    Test beam results of a calorimetric module based on 3×3×22 cm3 PbWO4 crystals, identical to those used in the CMS ECAL Endcaps, read out by a pair of photodetectors coupled to the two opposite sides (front and rear) of each crystal are presented. Nine crystals with different level of induced absorption, from 0 to 20 m‑1, have been tested using electrons in the 50–200 GeV energy range. Photomultiplier tubes have been chosen as photodetectors to allow for a precise measurement of highly damaged crystals. The information provided by this double side read-out configuration allows to correct for event-by-event fluctuations of the longitudinal development of electromagnetic showers. By strongly mitigating the effect of non-uniform light collection efficiency induced by radiation damage, the double side read-out technique significantly improves the energy resolution with respect to a single side read-out configuration. The non-linearity of the response arising in damaged crystals is also corrected by a double side read-out configuration and the response linearity of irradiated crystals is restored. In high radiation environments at future colliders, as it will be the case for detectors operating during the High Luminosity phase of the Large Hadron Collider, defects can be created inside the scintillator volume leading to a non-uniform response of the calorimetric cell. The double side read-out technique presented in this study provides a valuable way to improve the performance of calorimeters based on scintillators whose active volumes are characterized by high aspect ratio cells similar to those used in this study.

  6. Techniques for measuring vitamin A activity from β-carotene.

    PubMed

    Tang, Guangwen

    2012-11-01

    Dietary β-carotene is the most important precursor of vitamin A. However, the determination of the efficiency of in vivo conversion of β-carotene to vitamin A requires sensitive and safe techniques. It presents the following challenges: 1) circulating β-carotene concentration cannot be altered by eating a meal containing ≤6 mg β-carotene; 2) because retinol concentrations are homeostatically controlled, the conversion of β-carotene into vitamin A cannot be estimated accurately in well-nourished humans by assessing changes in serum retinol after supplementation with β-carotene. In the past half-century, techniques using radioisotopes of β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene supplements, measurement of postprandial chylomicron fractions after consumption of a β-carotene dose, and finally, stable isotopes as tracers to follow the absorption and conversion of β-carotene in humans have been developed. The reported values for β-carotene to vitamin A conversion showed a wide variation from 2 μg β-carotene to 1 μg retinol (for synthetic pure β-carotene in oil) and 28 μg β-carotene to 1 μg retinol (for β-carotene from vegetables). In recent years, a stable isotope reference method (IRM) was developed that used labeled synthetic β-carotene. The IRM method provided evidence that the conversion of β-carotene to vitamin A is likely dose dependent. With the development of intrinsically labeled plant foods harvested from a hydroponic system with heavy water, vitamin A activity of stable isotope-labeled biosynthetic β-carotene from various foods consumed by humans was studied. The efficacy of plant foods rich in β-carotene, such as natural (spinach, carrots, spirulina), hybrid (high-β-carotene yellow maize), and bioengineered (Golden Rice) foods, to provide vitamin A has shown promising results. The results from these studies will be of practical importance in recommendations for the use of pure β-carotene and foods

  7. A neutron activation technique for manganese measurements in humans.

    PubMed

    Bhatia, C; Byun, S H; Chettle, D R; Inskip, M J; Prestwich, W V

    2015-01-01

    Manganese (Mn) is an essential element for humans, animals, and plants and is required for growth, development, and maintenance of health. Studies show that Mn metabolism is similar to that of iron, therefore, increased Mn levels in humans could interfere with the absorption of dietary iron leading to anemia. Also, excess exposure to Mn dust, leads to nervous system disorders similar to Parkinson's disease. Higher exposure to Mn is essentially related to industrial pollution. Thus, there is a benefit in developing a clean non-invasive technique for monitoring such increased levels of Mn in order to understand the risk of disease and development of appropriate treatments. To this end, the feasibility of Mn measurements with their minimum detection limits (MDL) has been reported earlier from the McMaster group. This work presents improvement to Mn assessment using an upgraded system and optimized times of irradiation and counting for induced gamma activity of Mn. The technique utilizes the high proton current Tandetron accelerator producing neutrons via the (7)Li(p,n)(7)Be reaction at McMaster University and an array of nine NaI (Tl) detectors in a 4 π geometry for delayed counting of gamma rays. The neutron irradiation of a set of phantoms was performed with protocols having different proton energy, current and time of irradiation. The improved MDLs estimated using the upgraded set up and constrained timings are reported as 0.67 μgMn/gCa for 2.3 MeV protons and 0.71 μgMn/gCa for 2.0 MeV protons. These are a factor of about 2.3 times better than previous measurements done at McMaster University using the in vivo set-up. Also, because of lower dose-equivalent and a relatively close MDL, the combination of: 2.0 MeV; 300 μA; 3 min protocol is recommended as compared to 2.3 MeV; 400 μA; 45 s protocol for further measurements of Mn in vivo. PMID:25169978

  8. Internal sample attenuator counting (ISAC). A new technique for separating and measuring bound and free activity in radioimmunoassays

    SciTech Connect

    Thorell, J.I.

    1981-12-01

    A new method for the separation counting of bound and free activity in radioimmunoassays is described. Particles containing a radiation-abosrbing (attenuating) material are added to the assay. They shield the radiation from either the antibody-bound or the free radioligand. This obviates such manipulations conventionally involved in the separation and counting steps of radioimmunoassays as centrifugation decanting. Bismuth oxide is used as the attenuator. Particles with different properties are described. In one type, bismuth oxide is combined with active charcoal in an agarose matrix and serves as an absorbant for the free radioligand. In another type bismuth oxide is trapped within a polyacrylamide matrix to which antibodies are coupled. This particle can be used with a first- or a second-antibody bound activity. Application of the technique is illustrated with radioimmunoassays for thyroxin, triiodothyronine, human choriogonadotropin, and lutropin (luteinizing hormone).

  9. [Radiotherapy Techniques and Radiation Pneumonitis: A Lot To A Little Or A Little To A Lot?].

    PubMed

    Yu, Bingqi; Wang, Jin; Xu, Yujin; Su, Feng; Shan, Guoping; Chen, Ming

    2015-12-01

    Radiotherapy is one of the main treatment for patients with lung cancer. Three-dimensional conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) are widely used to deliver radiation. Here, we focus on the correlations between dose distribution in lung and radiation pneumonitis according to the analysis about radiotherapy for lung cancer: A lot to a little or a little to a lot, which is the main cause of radiation pneumonitis? PMID:26706952

  10. Spectral and Non Radiative Decay Studies of Lead Di Bromide Single Crystals by Mode Matched Thermal Lens Technique.

    PubMed

    Rejeena, I; Lillibai, B; Thomas, V; Nampoori, V P N; Radhakrishnan, P

    2016-07-01

    In the present paper, the investigations on the non radiative decay mechanism, optical band gap determination from absorption spectroscopic studies and fluorescence emission by photo luminescence techniques using different excitation wavelengths on gel derived lead di bromide single crystals are reported. Non radiative decay of the sample is studied using high sensitive dual beam mode matched thermal lens technique. For the thermal lensing experiment the crystal in solution phase is incorporated with rhodamine 6G dye for enhancing the absorption of the crystal sample. The thermal diffusivity of lead di bromide is determined using the probe beam intensity v/s time measurements. PMID:27165040

  11. Simplified techniques to study components of solar radiation under haze and clouds

    SciTech Connect

    Wesely, M.L.

    1982-03-01

    Estimates of the global (G), diffuse (D) and direct-beam (I) irradiances at the surface of the earth can be obtained with a single instrument, ''dial'' radiometer. The dial assembly intermittently shades a solid-state sensor on a continual automatic basis. This is a very simple instrument that does not require mechanical adjustments of the shade. When corrections for imperfect cosine response and excessive shading of sky radiation are performed, measurements averaged over 1 h should be accurate well within +- 5%. Estimates of atmospheric turbidity or haziness can be expressed as an extinction coefficient, computed for I in reference to that obtained under cloudless clean skies for the same solar zenith angle. The uneven spectral response of silicon-cell and PAR (photosynthetically active radiation) sensors should be considered when comparing estimates of G, D or I to measurments of these components by a wide-band sensor. Linear relationships seem adequate for a variety of cloud conditions. This allows the use of single dial silicon-cell radiometer, for example, to estimate quite accurately the values of G, D and I that would be seen by wide-band or PAR radiometers. An alternative, but less exact, means of obtaining estimates of hourly averages of D and I is to measure only G and use the ratio of G to that which would be obtained under clean, cloudless conditions as the sole determining factors.

  12. CHARACTERIZATION OF AN ACTIVELY COOLED METAL FOIL THERMAL RADIATION SHIELD

    SciTech Connect

    Feller, J. R.; Salerno, L. J.; Kashani, A.; Helvensteijn, B. P. M.

    2010-04-09

    Zero boil-off (ZBO) or reduced boil-off (RBO) systems that involve active cooling of large cryogenic propellant tanks will most likely be required for future space exploration missions. For liquid oxygen or methane, such systems could be implemented using existing high technology readiness level (TRL) cryocoolers. However, for liquid hydrogen temperatures (approx20 K) no such coolers exist. In order to partially circumvent this technology gap, the concept of broad area cooling (BAC) has been developed, whereby a low mass thermal radiation shield could be maintained at temperatures around 100 K by steady circulation of cold pressurized gas through a network of narrow tubes. By this method it is possible to dramatically reduce the radiative heat leak to the 20 K tank. A series of experiments, designed to investigate the heat transfer capabilities of BAC systems, have been conducted at NASA Ames Research Center (ARC). Results of the final experiment in this series, investigating heat transfer from a metal foil film to a distributed cooling line, are presented here.

  13. Characterization of AN Actively Cooled Metal Foil Thermal Radiation Shield

    NASA Astrophysics Data System (ADS)

    Feller, J. R.; Kashani, A.; Helvensteijn, B. P. M.; Salerno, L. J.

    2010-04-01

    Zero boil-off (ZBO) or reduced boil-off (RBO) systems that involve active cooling of large cryogenic propellant tanks will most likely be required for future space exploration missions. For liquid oxygen or methane, such systems could be implemented using existing high technology readiness level (TRL) cryocoolers. However, for liquid hydrogen temperatures (˜20 K) no such coolers exist. In order to partially circumvent this technology gap, the concept of broad area cooling (BAC) has been developed, whereby a low mass thermal radiation shield could be maintained at temperatures around 100 K by steady circulation of cold pressurized gas through a network of narrow tubes. By this method it is possible to dramatically reduce the radiative heat leak to the 20 K tank. A series of experiments, designed to investigate the heat transfer capabilities of BAC systems, have been conducted at NASA Ames Research Center (ARC). Results of the final experiment in this series, investigating heat transfer from a metal foil film to a distributed cooling line, are presented here.

  14. Spectral estimators of absorbed photosynthetically active radiation in corn canopies

    NASA Technical Reports Server (NTRS)

    Gallo, K. P.; Daughtry, C. S. T.; Bauer, M. E.

    1985-01-01

    Most models of crop growth and yield require an estimate of canopy leaf area index (LAI) or absorption of radiation. Relationships between photosynthetically active radiation (PAR) absorbed by corn canopies and the spectral reflectance of the canopies were investigated. Reflectance factor data were acquired with a Landsat MSS band radiometer. From planting to silking, the three spectrally predicted vegetation indices examined were associated with more than 95 percent of the variability in absorbed PAR. The relationships developed between absorbed PAR and the three indices were evaluated with reflectance factor data acquired from corn canopies planted in 1979 through 1982. Seasonal cumulations of measured LAI and each of the three indices were associated with greater than 50 percent of the variation in final grain yields from the test years. Seasonal cumulations of daily absorbed PAR were associated with up to 73 percent of the variation in final grain yields. Absorbed PAR, cumulated through the growing season, is a better indicator of yield than cumulated leaf area index. Absorbed PAR may be estimated reliably from spectral reflectance data of crop canopies.

  15. Spectral estimators of absorbed photosynthetically active radiation in corn canopies

    NASA Technical Reports Server (NTRS)

    Gallo, K. P.; Daughtry, C. S. T.; Bauer, M. E.

    1984-01-01

    Most models of crop growth and yield require an estimate of canopy leaf area index (LAI) or absorption of radiation. Relationships between photosynthetically active radiation (PAR) absorbed by corn canopies and the spectral reflectance of the canopies were investigated. Reflectance factor data were acquired with a LANDSAT MSS band radiometer. From planting to silking, the three spectrally predicted vegetation indices examined were associated with more than 95% of the variability in absorbed PAR. The relationships developed between absorbed PAR and the three indices were evaluated with reflectance factor data acquired from corn canopies planted in 1979 through 1982. Seasonal cumulations of measured LAI and each of the three indices were associated with greater than 50% of the variation in final grain yields from the test years. Seasonal cumulations of daily absorbed PAR were associated with up to 73% of the variation in final grain yields. Absorbed PAR, cumulated through the growing season, is a better indicator of yield than cumulated leaf area index. Absorbed PAR may be estimated reliably from spectral reflectance data of crop canopies.

  16. Photosynthetically active radiation and its relationship with global solar radiation in Central China.

    PubMed

    Wang, Lunche; Gong, Wei; Ma, Yingying; Hu, Bo; Zhang, Miao

    2014-08-01

    Photosynthetically active radiation (PAR) and other solar components were observed for a period of 3 years at Wuhan, China to determine for the first time the temporal variability of PAR fraction [PAR/G (G here stands for global solar radiation)] and its dependence on different sky conditions in Central China. PAR, G and PAR/G showed similar seasonal features that peaked in summer and reached their lowest values in winter. The seasonal PAR/G ranged from 1.70 E MJ(-1) (winter) to 2.01 E MJ(-1) (summer) with an annual mean value of 1.89 E MJ(-1). Hourly values of PAR/G increased from 1.78 to 2.11 E MJ(-1) on average as sky conditions changed from clear to cloudy. Monthly mean hourly PAR/G revealed a diurnal variation, with highest values observed around sunrise and sunset, slightly higher PAR fractions were also found around noon for most months. The effect of daylength on PAR/G was also studied and no significant impact was found. Three models were developed to estimate PAR from G. These models consisted of atmospheric parameters that were found to cause substantial changes of PAR/G, such as sky clearness, brightness, path length and the sky clearness index. The estimations obtained from different models were very close to the measured values with maximum relative errors below 8 % (hourly values) in Wuhan. The models were not only tested at seven radiation stations in Central China, but also verified in six stations with different climates in China. The models were found to estimate PAR accurately from commonly available G data in Central China; however, the results also implied that the models need to be modified to account for local climatic conditions when applied to the whole country. PMID:23780493

  17. Digital holographic interferometry: A novel optical calorimetry technique for radiation dosimetry

    SciTech Connect

    Cavan, Alicia; Meyer, Juergen

    2014-02-15

    Purpose: To develop and demonstrate the proof-of-principle of a novel optical calorimetry method to determine radiation absorbed dose in a transparent medium. Methods: The calorimetric property of water is measured during irradiation by means of an interferometer, which detects temperature-induced changes in the refractive index that can be mathematically related to absorbed dose. The proposed method uses a technique called digital holographic interferometry (DHI), which comprises an optical laser interferometer setup and consecutive physical reconstruction of the recorded wave fronts by means of the Fresnel transform. This paper describes the conceptual framework and provides the mathematical basis for DHI dosimetry. Dose distributions from a high dose rate Brachytherapy source were measured by a prototype optical setup to demonstrate the feasibility of the approach. Results: The developed DHI dosimeter successfully determined absorbed dose distributions in water in the region adjacent to a high dose rate Brachytherapy source. A temperature change of 0.0381 K across a distance of 6.8 mm near the source was measured, corresponding to a dose of 159.3 Gy. The standard deviation in a typical measurement set was ±3.45 Gy (corresponding to an uncertainty in the temperature value of ±8.3 × 10{sup −4} K). The relative dose fall off was in agreement with treatment planning system modeled data. Conclusions: First results with a prototype optical setup and a Brachytherapy source demonstrate the proof-of-principle of the approach. The prototype achieves high spatial resolution of approximately 3 × 10{sup −5} m. The general approach is fundamentally independent of the radiation type and energy. The sensitivity range determined indicates that the method is predominantly suitable for high dose rate applications. Further work is required to determine absolute dose in all three dimensions.

  18. Quantifying reflectance anisotropy of photosynthetically active radiation in grasslands

    SciTech Connect

    Middleton, E.M. )

    1992-11-30

    This work is part of the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE), an international land-surface-atmosphere experiment aimed at improving the way climate models represent energy, water, heat, and carbon exchanges, and improving the utilization of satellite based remote sensing to monitor such parameters. This paper reports on a study to quantify the reflectance anisotropy of the photosynthetically active radiation (PAR) for grasslands. PAR falls in the wavelength range 0.4 to 0.7[mu]m. The study looks at the variation of PAR with illumination and vegetative canopy conditions. It uses bidirectional reflectance distribution function data, and measures of anisotropy derived from reflectance factor and reflectance fraction data to aid in the analysis. The data used for this analysis came from an intense effort mounted to measure diurnal changes in the anisotropy of surface reflectance from prairie grassland as a function of the vegetative canopy.

  19. Neutron radiation tolerance of Au-activated silicon

    NASA Technical Reports Server (NTRS)

    Joyner, W. T.

    1987-01-01

    Double injection devices prepared by the introduction of deep traps, using the Au activation method have been found to tolerate gamma irradiation into the Gigarad (Si) region without significant degradation of operating characteristics. Silicon double injection devices, using deep levels creacted by Au diffusion, can tolerate fast neutron irradiation up to 10 to the 15th n/sq cm. Significant parameter degradation occurs at 10 to the 16th n/sq cm. However, since the actual doping of the basic material begins to change as a result of the transmutation of silicon into phosphorus for neutron fluences greater than 10 to the 17th/sq cm, the radiation tolerance of these devices is approaching the limit possible for any device based on initially doped silicon.

  20. Intercepted photosynthetically active radiation estimated by spectral reflectance

    NASA Technical Reports Server (NTRS)

    Hatfield, J. L.; Asrar, G.; Kanemasu, E. T.

    1984-01-01

    Interception of photosynthetically active radiation (PAR) was evaluated relative to greenness and normalized difference (MSS (7-5)/(7+5) for five planting dates of wheat for 1978-79 and 1979-80 at Phoenix, Arizona. Intercepted PAR was calculated from leaf area index and stage of growth. Linear relatinships were found with greeness and normalized difference with separate relatinships describing growth and senescence of the crop. Normalized difference was significantly better than greenness for all planting dates. For the leaf area growth portion of the season the relation between PAR interception and normalized difference was the same over years and planting dates. For the leaf senescence phase the relationships showed more variability due to the lack of data on light interception in sparse and senescing canopies. Normalized difference could be used to estimate PAR interception throughout a growing season.

  1. Treatment Techniques to Reduce Cardiac Irradiation for Breast Cancer Patients Treated with Breast-Conserving Surgery and Radiation Therapy: A Review

    PubMed Central

    Beck, Robert E.; Kim, Leonard; Yue, Ning J.; Haffty, Bruce G.; Khan, Atif J.; Goyal, Sharad

    2014-01-01

    Thousands of women diagnosed with breast cancer each year receive breast-conserving surgery followed by adjuvant radiation therapy. For women with left-sided breast cancer, there is risk of potential cardiotoxicity from the radiation therapy. As data have become available to quantify the risk of cardiotoxicity from radiation, strategies have also developed to reduce the dose of radiation to the heart without compromising radiation dose to the breast. Several broad categories of techniques to reduce cardiac radiation doses include breath hold techniques, prone positioning, intensity-modulated radiation therapy, and accelerated partial breast irradiation, as well as many small techniques to improve traditional three-dimensional conformal radiation therapy. This review summarizes the published scientific literature on the various techniques to decrease cardiac irradiation in women treated to the left breast for breast cancer after breast-conserving surgery. PMID:25452938

  2. Risk of Second Cancers According to Radiation Therapy Technique and Modality in Prostate Cancer Survivors

    SciTech Connect

    Berrington de Gonzalez, Amy; Wong, Jeannette; Kleinerman, Ruth; Kim, Clara; Morton, Lindsay; Bekelman, Justin E.

    2015-02-01

    Purpose: Radiation therapy (RT) techniques for prostate cancer are evolving rapidly, but the impact of these changes on risk of second cancers, which are an uncommon but serious consequence of RT, are uncertain. We conducted a comprehensive assessment of risks of second cancer according to RT technique (>10 MV vs ≤10 MV and 3-dimensional [3D] vs 2D RT) and modality (external beam RT, brachytherapy, and combined modes) in a large cohort of prostate cancer patients. Methods and Materials: The cohort was constructed using the Surveillance Epidemiology and End Results-Medicare database. We included cases of prostate cancer diagnosed in patients 66 to 84 years of age from 1992 to 2004 and followed through 2009. We used Poisson regression analysis to compare rates of second cancer across RT groups with adjustment for age, follow-up, chemotherapy, hormone therapy, and comorbidities. Analyses of second solid cancers were based on the number of 5-year survivors (n=38,733), and analyses of leukemia were based on number of 2-year survivors (n=52,515) to account for the minimum latency period for radiation-related cancer. Results: During an average of 4.4 years' follow-up among 5-year prostate cancer survivors (2DRT = 5.5 years; 3DRT = 3.9 years; and brachytherapy = 2.7 years), 2933 second solid cancers were diagnosed. There were no significant differences in second solid cancer rates overall between 3DRT and 2DRT patients (relative risk [RR] = 1.00, 95% confidence interval [CI]: 0.91-1.09), but second rectal cancer rates were significantly lower after 3DRT (RR = 0.59, 95% CI: 0.40-0.88). Rates of second solid cancers for higher- and lower-energy RT were similar overall (RR = 0.97, 95% CI: 0.89-1.06), as were rates for site-specific cancers. There were significant reductions in colon cancer and leukemia rates in the first decade after brachytherapy compared to those after external beam RT. Conclusions: Advanced treatment planning may have reduced rectal

  3. Successful Application of Active Learning Techniques to Introductory Microbiology.

    ERIC Educational Resources Information Center

    Hoffman, Elizabeth A.

    2001-01-01

    Points out the low student achievement in microbiology courses and presents an active learning method applied in an introductory microbiology course which features daily quizzes, cooperative learning activities, and group projects. (Contains 30 references.) (YDS)

  4. INVESTIGATION OF MICROSCOPIC RADIATION DAMAGE IN WASTE FORMS USING ODNMR AND AEM TECHNIQUES

    EPA Science Inventory

    The proposed project addresses DOE nuclear waste problems that are currently intractable without achieving a fundamental understanding of radiation effects on high level waste (HLW) forms. This project will investigate the microscopic effects of radiation damage in crystalline an...

  5. A technique for estimating the probability of radiation-stimulated failures of integrated microcircuits in low-intensity radiation fields: Application to the Spektr-R spacecraft

    NASA Astrophysics Data System (ADS)

    Popov, V. D.; Khamidullina, N. M.

    2006-10-01

    In developing radio-electronic devices (RED) of spacecraft operating in the fields of ionizing radiation in space, one of the most important problems is the correct estimation of their radiation tolerance. The “weakest link” in the element base of onboard microelectronic devices under radiation effect is the integrated microcircuits (IMC), especially of large scale (LSI) and very large scale (VLSI) degree of integration. The main characteristic of IMC, which is taken into account when making decisions on using some particular type of IMC in the onboard RED, is the probability of non-failure operation (NFO) at the end of the spacecraft’s lifetime. It should be noted that, until now, the NFO has been calculated only from the reliability characteristics, disregarding the radiation effect. This paper presents the so-called “reliability” approach to determination of radiation tolerance of IMC, which allows one to estimate the probability of non-failure operation of various types of IMC with due account of radiation-stimulated dose failures. The described technique is applied to RED onboard the Spektr-R spacecraft to be launched in 2007.

  6. A Instrument and Technique for Measuring the Anisotropy in the Cosmic Microwave Background Radiation

    NASA Astrophysics Data System (ADS)

    Wilson, Grant W.

    1997-09-01

    There is a wealth of information contained in the spatial temperature distribution of the Cosmic Microwave Background Radiation (CMB) >From the pioneering discovery of anisotropy by the COBE satellite to the latest balloon payloads and ground based observations, measurements of the CMB have become the cornerstone of our current understanding of the Universe. Currently, the second generation of CMB experiments are coming on-line. With improved detectors and novel observing strategies, these experiments are destined to make the transition from 'discovering' the anisotropy in the CMB to making precision measurements of the spatial correlation function. Herein I describe the most recent of these second generation experiments: the Medium Scale Anisotropy Measurement (MSAM II). MSAM II is a balloon-based telescope with a bolometric receiver cooled by an Adiabatic Demagnetization Refrigerator to 100 mK. MSAM II samples the sky with a 20 prime FWHM beam swept with a triangle wave at 2.5 Hz and will make a precision measurement of the spatial correlation function from 1 = 100 to 1 = 500. In addition to a comprehensive discussion of the fabrication and development of the cryogenic and optical systems of MSAM II, I present a novel method of estimating cosmological parameters from anisotropy measurements using a maximum Likelihood technique which employs the full covariance matrix of observations. This method has been used on the combined three years of MSAM I datasets to constrain the mass fraction of baryons in the universe, ΩB, as well as a number of other cosmological parameters.

  7. Use of image guided radiation therapy techniques and imaging dose measurement at Indian hospitals: A survey

    PubMed Central

    Deshpande, Sudesh; Dhote, D. S.; Kumar, Rajesh; Naidu, Suresh; Sutar, A.; Kannan, V.

    2015-01-01

    A national survey was conducted to obtain information about the use of image-guided radiotherapy (IGRT) techniques and IGRT dose measurement methods being followed at Indian radiotherapy centers. A questionnaire containing parameters relevant to use of IGRT was prepared to collect the information pertaining to (i) availability and type of IGRT delivery system, (ii) frequency of image acquisition protocol and utilization of these images for different purpose, and (iii) imaging dose measurement. The questionnaire was circulated to 75 hospitals in the country having IGRT facility, and responses of 51 centers were received. Survey results showed that among surveyed hospitals, 86% centers have IGRT facility, 78% centers have kilo voltage three-dimensional volumetric imaging. 75% of hospitals in our study do not perform computed tomography dose index measurements and 89% of centers do not perform patient dose measurements. Moreover, only 29% physicists believe IGRT dose is additional radiation burden to patient. This study has brought into focus the need to design a national protocol for IGRT dose measurement and development of indigenous tools to perform IGRT dose measurements. PMID:26865758

  8. Comparison of the effectiveness of some common animal data scaling techniques in estimating human radiation dose

    SciTech Connect

    Sparks, R.B.; Aydogan, B.

    1999-01-01

    In the development of new radiopharmaceuticals, animal studies are typically performed to get a first approximation of the expected radiation dose in humans. This study evaluates the performance of some commonly used data extrapolation techniques to predict residence times in humans using data collected from animals. Residence times were calculated using animal and human data, and distributions of ratios of the animal results to human results were constructed for each extrapolation method. Four methods using animal data to predict human residence times were examined: (1) using no extrapolation, (2) using relative organ mass extrapolation, (3) using physiological time extrapolation, and (4) using a combination of the mass and time methods. The residence time ratios were found to be log normally distributed for the nonextrapolated and extrapolated data sets. The use of relative organ mass extrapolation yielded no statistically significant change in the geometric mean or variance of the residence time ratios as compared to using no extrapolation. Physiologic time extrapolation yielded a statistically significant improvement (p < 0.01, paired t test) in the geometric mean of the residence time ratio from 0.5 to 0.8. Combining mass and time methods did not significantly improve the results of using time extrapolation alone. 63 refs., 4 figs., 3 tabs.

  9. Use of image guided radiation therapy techniques and imaging dose measurement at Indian hospitals: A survey.

    PubMed

    Deshpande, Sudesh; Dhote, D S; Kumar, Rajesh; Naidu, Suresh; Sutar, A; Kannan, V

    2015-01-01

    A national survey was conducted to obtain information about the use of image-guided radiotherapy (IGRT) techniques and IGRT dose measurement methods being followed at Indian radiotherapy centers. A questionnaire containing parameters relevant to use of IGRT was prepared to collect the information pertaining to (i) availability and type of IGRT delivery system, (ii) frequency of image acquisition protocol and utilization of these images for different purpose, and (iii) imaging dose measurement. The questionnaire was circulated to 75 hospitals in the country having IGRT facility, and responses of 51 centers were received. Survey results showed that among surveyed hospitals, 86% centers have IGRT facility, 78% centers have kilo voltage three-dimensional volumetric imaging. 75% of hospitals in our study do not perform computed tomography dose index measurements and 89% of centers do not perform patient dose measurements. Moreover, only 29% physicists believe IGRT dose is additional radiation burden to patient. This study has brought into focus the need to design a national protocol for IGRT dose measurement and development of indigenous tools to perform IGRT dose measurements. PMID:26865758

  10. Radiative neutron capture as a counting technique at pulsed spallation neutron sources: a review of current progress.

    PubMed

    Schooneveld, E M; Pietropaolo, A; Andreani, C; Perelli Cippo, E; Rhodes, N J; Senesi, R; Tardocchi, M; Gorini, G

    2016-09-01

    Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources. PMID:27502571

  11. Radiative neutron capture as a counting technique at pulsed spallation neutron sources: a review of current progress

    NASA Astrophysics Data System (ADS)

    Schooneveld, E. M.; Pietropaolo, A.; Andreani, C.; Perelli Cippo, E.; Rhodes, N. J.; Senesi, R.; Tardocchi, M.; Gorini, G.

    2016-09-01

    Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources.

  12. Technique factors and their relationship to radiation dose in pendant geometry breast CT

    SciTech Connect

    Boone, John M.; Kwan, Alexander L. C.; Seibert, J. Anthony; Shah, Nikula; Lindfors, Karen K.; Nelson, Thomas R.

    2005-12-15

    The use of breast computed tomography (CT) as an alternative to mammography in some patients is being studied at several institutions. However, the radiation dosimetry issues associated with breast CT are markedly different than in the case of mammography. In this study, the spectral properties of an operational breast CT scanner were characterized both by physical measurement and computer modeling of the kVp-dependent spectra, from 40 to 110 kVp (Be window W anode with 0.30 mm added Cu filtration). Previously reported conversion factors, normalized glandular dose for CT-DgN(ct), derived from Monte Carlo methods, were used in concert with the output spectra of the breast scanner to compute the mean glandular dose to the breast based upon different combinations of x-ray technique factors (kVp and mAs). The mean glandular dose (MGD) was measured as a function of the compressed breast thickness (2-8 cm) and three different breast compositions (0%, 50%, and 100% glandular fractions) in four clinical mammography systems in our institution. The average MGD from these four systems was used to compute the technique factors for breast CT systems that would match the two-view mammographic dose levels. For a 14 cm diameter breast (equivalent to a 5 cm thick compressed breast in mammography), air kerma levels at the breast CT scanner's isocenter (468 mm from the source) of 4.4, 6.4, and 9.0 mGy were found to deliver equivalent mammography doses for 0%, 50%, and 100% glandular breasts (respectively) at 80 kVp. At 80 kVp (where air kerma was 11.3 mGy/100 mAs at the isocenter), 57 mAs (integrated over the entire scan) was required to match the mammography dose for a 14 cm 50% glandular breast. At 50 kVp, 360 mAs is required to match mammographic dose levels. Tables are provided for both air kerma at the isocenter and mAs for 0%, 50%, and 100% glandular breasts. Other issues that impact breast CT technique factors are also discussed.

  13. Stanford Synchrotron Radiation Laboratory. Activity report for 1988

    SciTech Connect

    Cantwell, K.

    1996-01-01

    For SSRL operations, 1988 was a year of stark contrasts. The first extended PEP parasitic running since the construction of our two beam lines on that storage ring took place in November and December. Four experiments discussed below, were performed and detailed operational procedures which allowed synchrotron radiation an high energy users to coexist were established. SSRL anticipates that there will be significant amounts of beam time when PEP is run again for high energy physics. On the other hand, activity on SPEAR consisted of brief parasitic running on the VUV lines in December when the ring was operated at 1.85 GeV for colliding beam experiments. There was no dedicated SPEAR running throughout the entire calendar year. This is the first time since dedicated SPEAR operation was initiated in 1980 that there was no such running. The decision was motivated by both cost and performance factors, as discussed in Section 1 of this report. Fortunately, SLAC and SSRL have reached an agreement on SPEAR and PEP dedicated time charges which eliminates the cost volatility which was so important in the cancellation of the June-July dedicated SPEAR run. As discussed in Section 2, the 3 GeV SPEAR injector construction is proceeding on budget and on schedule. The injector will overcome the difficulties associated with the SLC-era constraint of only two injections per day. SSR and SLAC have also embarked on a program to upgrade SPEAR to achieve high reliability and performance. As a consequence, SSRL`s users may anticipate a highly effective SPEAR by 1991, at the latest. At that time, SPEAR is expected to be fully dedicated to synchrotron radiation research and operated by SSRL. Also contained in this report is a discussion of the improvements to SSRL`s experimental facilities and highlights of the experiments of the past year.

  14. Evaluation of Four Techniques Using Intensity-Modulated Radiation Therapy for Comprehensive Locoregional Irradiation of Breast Cancer

    SciTech Connect

    Jagsi, Reshma; Moran, Jean; Marsh, Robin; Masi, Kathryn; Griffith, Kent A.; Pierce, Lori J.

    2010-12-01

    Purpose: To establish optimal intensity-modulated radiation therapy (IMRT) techniques for treating the left breast and regional nodes, using moderate deep-inspiration breath hold. Methods and Materials: We developed four IMRT plans of differing complexity for each of 10 patients following lumpectomy for left breast cancer. A dose of 60 Gy was prescribed to the boost planning target volume (PTV) and 52.2 Gy to the breast and supraclavicular, infraclavicular, and internal mammary nodes. Two plans used inverse-planned beamlet techniques: a 9-field technique, with nine equispaced axial beams, and a tangential beamlet technique, with three to five ipsilateral beams. The third plan (a segmental technique) used a forward-planned multisegment technique, and the fourth plan (a segmental blocked technique) was identical but included a block to limit heart dose. Dose--volume histograms were generated, and metrics chosen for comparison were analyzed using the paired t test. Results: Mean heart and left anterior descending coronary artery doses were similar with the tangential beamlet and segmental blocked techniques but higher with the segmental and 9-field techniques (mean paired difference of 15.1 Gy between segmental and tangential beamlet techniques, p < 0.001). Substantial volumes of contralateral tissue received dose with the 9-field technique (mean right breast V2, 58.9%; mean right lung V2, 75.3%). Minimum dose to {>=}95% of breast PTV was, on average, 45.9 Gy with tangential beamlet, 45.0 Gy with segmental blocked, 51.4 Gy with segmental, and 50.2 Gy with 9-field techniques. Coverage of the internal mammary region was substantially better with the two beamlet techniques than with the segmental blocked technique. Conclusions: Compared to the 9-field beamlet and segmental techniques, a tangential beamlet IMRT technique reduced exposure to normal tissues and maintained reasonable target coverage.

  15. Radiation-hard active CMOS pixel sensors for HL-LHC detector upgrades

    NASA Astrophysics Data System (ADS)

    Backhaus, Malte

    2015-02-01

    The luminosity of the Large Hadron Collider (LHC) will be increased during the Long Shutdown of 2022 and 2023 (LS3) in order to increase the sensitivity of its experiments. A completely new inner detector for the ATLAS experiment needs to be developed to withstand the extremely harsh environment of the upgraded, so-called High-Luminosity LHC (HL-LHC). High radiation hardness as well as granularity is mandatory to cope with the requirements in terms of radiation damage as well as particle occupancy. A new silicon detector concept that uses commercial high voltage and/or high resistivity full complementary metal-oxide-semiconductor (CMOS) processes as active sensor for pixel and/or strip layers has risen high attention, because it potentially provides high radiation hardness and granularity and at the same time reduced price due to the commercial processing and possibly relaxed requirements for the hybridization technique. Results on the first prototypes characterized in a variety of laboratory as well as test beam environments are presented.

  16. Investigation of Advanced Dose Verification Techniques for External Beam Radiation Treatment

    NASA Astrophysics Data System (ADS)

    Asuni, Ganiyu Adeniyi

    Intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) have been introduced in radiation therapy to achieve highly conformal dose distributions around the tumour while minimizing dose to surrounding normal tissues. These techniques have increased the need for comprehensive quality assurance tests, to verify that customized patient treatment plans are accurately delivered during treatment. in vivo dose verification, performed during treatment delivery, confirms that the actual dose delivered is the same as the prescribed dose, helping to reduce treatment delivery errors. in vivo measurements may be accomplished using entrance or exit detectors. The objective of this project is to investigate a novel entrance detector designed for in vivo dose verification. This thesis is separated into three main investigations, focusing on a prototype entrance transmission detector (TRD) developed by IBA Dosimetry, Germany. First contaminant electrons generated by the TRD in a 6 MV photon beam were investigated using Monte Carlo (MC) simulation. This study demonstrates that modification of the contaminant electron model in the treatment planning system is required for accurate patient dose calculation in buildup regions when using the device. Second, the ability of the TRD to accurately measure dose from IMRT and VMAT was investigated by characterising the spatial resolution of the device. This was accomplished by measuring the point spread function with further validation provided by MC simulation. Comparisons of measured and calculated doses show that the spatial resolution of the TRD allows for measurement of clinical IMRT fields within acceptable tolerance. Finally, a new general research tool was developed to perform MC simulations for VMAT and IMRT treatments, simultaneously tracking dose deposition in both the patient CT geometry and an arbitrary planar detector system, generalized to handle either entrance or exit orientations. It was

  17. Activated sampling in complex materials at finite temperature: The properly obeying probability activation-relaxation technique

    NASA Astrophysics Data System (ADS)

    Vocks, Henk; Chubynsky, M. V.; Barkema, G. T.; Mousseau, Normand

    2005-12-01

    While the dynamics of many complex systems is dominated by activated events, there are very few simulation methods that take advantage of this fact. Most of these procedures are restricted to relatively simple systems or, as with the activation-relaxation technique (ART), sample the conformation space efficiently at the cost of a correct thermodynamical description. We present here an extension of ART, the properly obeying probability ART (POP-ART), that obeys detailed balance and samples correctly the thermodynamic ensemble. Testing POP-ART on two model systems, a vacancy and an interstitial in crystalline silicon, we show that this method recovers the proper thermodynamical weights associated with the various accessible states and is significantly faster than molecular dynamics in the simulations of a vacancy below 700 K.

  18. Activated sampling in complex materials at finite temperature: the properly obeying probability activation-relaxation technique.

    PubMed

    Vocks, Henk; Chubynsky, M V; Barkema, G T; Mousseau, Normand

    2005-12-22

    While the dynamics of many complex systems is dominated by activated events, there are very few simulation methods that take advantage of this fact. Most of these procedures are restricted to relatively simple systems or, as with the activation-relaxation technique (ART), sample the conformation space efficiently at the cost of a correct thermodynamical description. We present here an extension of ART, the properly obeying probability ART (POP-ART), that obeys detailed balance and samples correctly the thermodynamic ensemble. Testing POP-ART on two model systems, a vacancy and an interstitial in crystalline silicon, we show that this method recovers the proper thermodynamical weights associated with the various accessible states and is significantly faster than molecular dynamics in the simulations of a vacancy below 700 K. PMID:16396563

  19. An iterative finite element-integral technique for predicting sound radiation from turbofan inlets in steady flight

    NASA Technical Reports Server (NTRS)

    Horowitz, S. J.; Sigman, R. K.; Zinn, B. T.

    1982-01-01

    A new iterative solution technique for predicting the sound field radiated from a turbofan inlet in steady flight is presented. The sound field is divided into two regions: the sound field within and near the inlet which is computed using the finite element method and the radiation field beyond the inlet which is calculated using an integral solution technique. A continuous solution is obtained by matching the finite element and integral solutions at the interface between the two regions. The applicability of the iterative technique is demonstrated by comparison of experimental results with the theoretical results for several different inlet configurations with and without flow. These examples show that good agreement between experiment and theory is obtained within five iterations.

  20. Radiation-induced signals of gypsum crystals analysed by ESR and TL techniques applied to dating

    NASA Astrophysics Data System (ADS)

    Aydaş, Canan; Engin, Birol; Aydın, Talat

    2011-02-01

    Natural crystals of terrestrial gypsum were investigated concerning the radiation effects on Electron spin resonance (ESR) and Thermoluminescence (TL) properties and their application for geological dating. ESR signals of Fe 3+, Mn 2+, G1 ( SO3-, g = 2.003) and G2 ( SO4-, g∥=2.018g⊥=2.009) centers were observed. The thermal stability and dose response of the ESR signals were found to be suitable for an age determination using a signal at g = 2.009. The intensity of this center increased with γ-radiation and the additive dose method for this ESR center yielded accumulated dose GD of 67.4 ± 10.1 Gy. Using U, Th and K contents plus the cosmic-ray contribution, a dose rate of 1.92 ± 0.22 mGy/year has been obtained. We have determined the ESR age of the gypsums to be (35 ± 4) × 10 3 years. TL peaks at 157 and 278 °C were observed. By using initial rise method the thermal activation energy of 278 °C TL peak was found to be underestimated, probably due to the thermal quenching. Activation energies and frequency factors obtained by the method of varying the heating rate indicate lifetime of 4.09 × 10 7 years (at 15 °C) for 278 °C peak. The additive dose method applied to this TL peak yielded GD of 75 ± 11 Gy. The corresponding TL age using the 278 °C TL peak was found to be (39 ± 5) × 10 3 years for gypsum sample. The TL age of this sample is consistent with the ESR age within experimental error limits. The obtained ESR and TL ages are not consistent with the expectations of geologists. This contradiction is probably due to the repeatedly recrystallisation of gypsum samples under the environmental conditions after their formation in the upper Miocene-Pliocene Epoch.

  1. Application of thermal analysis techniques in activated carbon production

    USGS Publications Warehouse

    Donnals, G.L.; DeBarr, J.A.; Rostam-Abadi, M.; Lizzio, A.A.; Brady, T.A.

    1996-01-01

    Thermal analysis techniques have been used at the ISGS as an aid in the development and characterization of carbon adsorbents. Promising adsorbents from fly ash, tires, and Illinois coals have been produced for various applications. Process conditions determined in the preparation of gram quantities of carbons were used as guides in the preparation of larger samples. TG techniques developed to characterize the carbon adsorbents included the measurement of the kinetics of SO2 adsorption, the performance of rapid proximate analyses, and the determination of equilibrium methane adsorption capacities. Thermal regeneration of carbons was assessed by TG to predict the life cycle of carbon adsorbents in different applications. TPD was used to determine the nature of surface functional groups and their effect on a carbon's adsorption properties.

  2. Mathematical analysis techniques for modeling the space network activities

    NASA Technical Reports Server (NTRS)

    Foster, Lisa M.

    1992-01-01

    The objective of the present work was to explore and identify mathematical analysis techniques, and in particular, the use of linear programming. This topic was then applied to the Tracking and Data Relay Satellite System (TDRSS) in order to understand the space network better. Finally, a small scale version of the system was modeled, variables were identified, data was gathered, and comparisons were made between actual and theoretical data.

  3. Innovative techniques in radiation oncology. Clinical research programs to improve local and regional control in cancer

    SciTech Connect

    Brady, L.W.; Markoe, A.M.; Micaily, B.; Fisher, S.A.; Lamm, F.R. )

    1990-02-01

    There is a growing importance in failure analysis in cancer management. In these analyses locoregional failure as the cause of death emerges as a significant problem in many tumor sites, e.g., head and neck cancer, gynecologic cancer, genitourinary cancer. Because of these data, the radiation oncology community has attributed high priority to research efforts to improve locoregional control. These efforts include the following: (1) brachytherapy alone or with external beam radiation therapy or surgery; (2) intraoperative radiation therapy; (3) hyperthermia with radiation therapy; (4) particle irradiation (protons, neutrons, stripped nuclei, and pions); and (5) routes of administration of the treatment, including infusional (intravenous) chemotherapy with radiation therapy, intraarterial monoclonal antibodies with radionuclides, and intraarterial chemotherapy with radiation therapy. Each area of investigation is discussed.

  4. The influence of curricular and extracurricular learning activities on students' choice of chiropractic technique

    PubMed Central

    Sikorski, David M.; KizhakkeVeettil, Anupama; Tobias, Gene S.

    2016-01-01

    Objective: Surveys for the National Board of Chiropractic Examiners indicate that diversified chiropractic technique is the most commonly used chiropractic manipulation method. The study objective was to investigate the influences of our diversified core technique curriculum, a technique survey course, and extracurricular technique activities on students' future practice technique preferences. Methods: We conducted an anonymous, voluntary survey of 1st, 2nd, and 3rd year chiropractic students at our institution. Surveys were pretested for face validity, and data were analyzed using descriptive and inferential statistics. Results: We had 164 students (78% response rate) participate in the survey. Diversified was the most preferred technique for future practice by students, and more than half who completed the chiropractic technique survey course reported changing their future practice technique choice as a result. The students surveyed agreed that the chiropractic technique curriculum and their experiences with chiropractic practitioners were the two greatest bases for their current practice technique preference, and that their participation in extracurricular technique clubs and seminars was less influential. Conclusions: Students appear to have the same practice technique preferences as practicing chiropractors. The chiropractic technique curriculum and the students' experience with chiropractic practitioners seem to have the greatest influence on their choice of chiropractic technique for future practice. Extracurricular activities, including technique clubs and seminars, although well attended, showed a lesser influence on students' practice technique preferences. PMID:26655282

  5. Application of the planar-scanning technique to the near-field dosimetry of millimeter-wave radiators.

    PubMed

    Zhao, Jianxun; Lu, Hongmin; Deng, Jun

    2015-02-01

    The planar-scanning technique was applied to the experimental measurement of the electric field and power flux density (PFD) in the exposure area close to the millimeter-wave (MMW) radiator. In the near-field region, the field and PFD were calculated from the plane-wave spectrum of the field sampled on a scan plane far from the radiator. The measurement resolution was improved by reducing the spatial interval between the field samples to a fraction of half the wavelength and implementing multiple iterations of the fast Fourier transform. With the reference to the results from the numerical calculation, an experimental evaluation of the planar-scanning measurement was made for a 50 GHz radiator. Placing the probe 1 to 3 wavelengths from the aperture of the radiator, the direct measurement gave the near-field data with significant differences from the numerical results. The planar-scanning measurement placed the probe 9 wavelengths away from the aperture and effectively reduced the maximum and averaged differences in the near-field data by 70.6% and 65.5%, respectively. Applied to the dosimetry of an open-ended waveguide and a choke ring antenna for 60 GHz exposure, the technique proved useful to the measurement of the PFD in the near-field exposure area of MMW radiators. PMID:25644219

  6. A simulation study investigating a radiation detector utilizing the prompt gamma range verification technique for proton radiotherapy

    NASA Astrophysics Data System (ADS)

    Lau, Andrew David

    Proton therapy has shown to be a viable therapy for radiation oncology applications. The advantages of using protons as compared to photons in the treatments of diseases with radiation are numerous including the ability to deliver overall lower amounts of lethal radiation doses to the patient. This advantage is due to the fundamental interaction mechanism of the incident therapeutic protons with the patient, which produces a characteristic dose-distribution unique only to protons. Unlike photons, the entire proton beam is absorbed within the patent and the dose-distribution's maximum occurs near the end of the proton's path. Protons deliver less dose on the skin and intervening tissues, tighter dose conformality to the disease site, as well as no dose past the target volume, sparring healthy tissue distally in the patient. Current research in proton therapy is geared towards minimizing proton range uncertainty and monitoring in-vivo the location of the proton's path. Monitoring the beam's path serves also to verify which healthy structures/tissues were irradiated and whether the target volume has met the prescription dose. Among the many techniques used for in-vivo proton monitoring, the technique based on the emitted secondary particles, specifically the Prompt Gamma (PG) method, can be used for clinical implementation. This work focuses on developing a radiation detector system for using the PG method by investigating the characterizing the secondary particle field emitted from plastic and water phantoms as well as a radiation detector based on glass materials that exploits the Cherenkov phenomenon.

  7. Reduction in radiation dose with reconstruction technique in the brain perfusion CT

    NASA Astrophysics Data System (ADS)

    Kim, H. J.; Lee, H. K.; Song, H.; Ju, M. S.; Dong, K. R.; Chung, W. K.; Cho, M. S.; Cho, J. H.

    2011-12-01

    The principal objective of this study was to verify the utility of the reconstruction imaging technique in the brain perfusion computed tomography (PCT) scan by assessing reductions in the radiation dose and analyzing the generated images. The setting used for image acquisition had a detector coverage of 40 mm, a helical thickness of 0.625 mm, a helical shuttle mode scan type and a rotation time of 0.5 s as the image parameters used for the brain PCT scan. Additionally, a phantom experiment and an animal experiment were carried out. In the phantom and animal experiments, noise was measured in the scanning with the tube voltage fixed at 80 kVp (kilovolt peak) and the level of the adaptive statistical iterative reconstruction (ASIR) was changed from 0% to 100% at 10% intervals. The standard deviation of the CT coefficient was measured three times to calculate the mean value. In the phantom and animal experiments, the absorbed dose was measured 10 times under the same conditions as the ones for noise measurement before the mean value was calculated. In the animal experiment, pencil-type and CT-dedicated ionization chambers were inserted into the central portion of pig heads for measurement. In the phantom study, as the level of the ASIR changed from 0% to 100% under identical scanning conditions, the noise value and dose were proportionally reduced. In our animal experiment, the noise value was lowest when the ASIR level was 50%, unlike in the phantom study. The dose was reduced as in the phantom study.

  8. Determination of Jet Noise Radiation Source Locations using a Dual Sideline Cross-Correlation/Spectrum Technique

    NASA Technical Reports Server (NTRS)

    Allen, C. S.; Jaeger, S. M.

    1999-01-01

    The goal of our efforts is to extrapolate nearfield jet noise measurements to the geometric far field where the jet noise sources appear to radiate from a single point. To accomplish this, information about the location of noise sources in the jet plume, the radiation patterns of the noise sources and the sound pressure level distribution of the radiated field must be obtained. Since source locations and radiation patterns can not be found with simple single microphone measurements, a more complicated method must be used.

  9. Optimization of Radiation Therapy Techniques for Prostate Cancer With Prostate-Rectum Spacers: A Systematic Review

    SciTech Connect

    Mok, Gary; Benz, Eileen; Vallee, Jean-Paul; Miralbell, Raymond; Zilli, Thomas

    2014-10-01

    Dose-escalated radiation therapy for localized prostate cancer improves disease control but is also associated with worse rectal toxicity. A spacer placed between the prostate and rectum can be used to displace the anterior rectal wall outside of the high-dose radiation regions and potentially minimize radiation-induced rectal toxicity. This systematic review focuses on the published data regarding the different types of commercially available prostate-rectum spacers. Dosimetric results and preliminary clinical data using prostate-rectum spacers in patients with localized prostate cancer treated by curative radiation therapy are compared and discussed.

  10. Advanced radiation techniques for inspection of diesel engine combustion chamber materials components. Final report

    SciTech Connect

    1995-10-09

    Heavy duty truck engines must meet stringent life cycle cost and regulatory requirements. Meeting these requirements has resulted in convergence on 4-stroke 6-in-line, turbocharged, and after-cooled engines with direct-injection combustion systems. These engines provide much higher efficiencies (42%, fuel consumption 200 g/kW-hr) than automotive engines (31%, fuel consumption 270 g/kW-hr), but at higher initial cost. Significant near-term diesel engine improvements are necessary and are spurred by continuing competitive, Middle - East oil problems and Congressional legislation. As a result of these trends and pressures, Caterpillar has been actively pursuing a low-fuel consumption engine research program with emphasis on product quality through process control and product inspection. The goal of this project is to combine the nondestructive evaluation and computational resources and expertise available at LLNL with the diesel engine and manufacturing expertise of the Caterpillar Corporation to develop in-process monitoring and inspection techniques for diesel engine combustion chamber components and materials. Early development of these techniques will assure the optimization of the manufacturing process by design/inspection interface. The transition from the development stage to the manufacturing stage requires a both a thorough understanding of the processes and a way of verifying conformance to process standards. NDE is one of the essential tools in accomplishing both elements and in this project will be integrated with Caterpillar`s technological and manufacturing expertise to accomplish the project goals.

  11. An experimental search for gamma radiation associated with thunderstorm activity

    SciTech Connect

    Fryberger, D.

    1992-11-01

    This experiment is a repeat of an earlier experiment, but with more sensitive apparatus and in a location with a higher incidence of thunderstorm activity. The earlier experiment was undertaken by Ashby and Whitehead to investigate the theory that ball lightning might be associated with the annihilation of small amounts of antimatter, and it yielded some very interesting but inconclusive results. In the course of about 12 months of data taking, four high rate bursts of gamma radiation were detected. These events lasted a few seconds and had many thousands of counts (16500, 5000, 3700, and [gt] 7700. Unfortunately, the association of these gamma ray bursts with thunderstorms or ball lightning was not clearly established, although one of the bursts did occur during a local thunderstorm in rough coincidence with a lightning bolt striking a flagpole about 100 yards from the gamma ray detection crystals. A pulse height spectrum taken for this burst (no spectrum was taken for the other three) exhibited a significant peak, well above background, the energy of which appeared to be compatible with the 511 keV positron annihilation line. While the peak could not be unambiguously attributed to positron annihilation, this certainly appeared to be the most likely source.

  12. An experimental search for gamma radiation associated with thunderstorm activity

    SciTech Connect

    Fryberger, D.

    1992-11-01

    This experiment is a repeat of an earlier experiment, but with more sensitive apparatus and in a location with a higher incidence of thunderstorm activity. The earlier experiment was undertaken by Ashby and Whitehead to investigate the theory that ball lightning might be associated with the annihilation of small amounts of antimatter, and it yielded some very interesting but inconclusive results. In the course of about 12 months of data taking, four high rate bursts of gamma radiation were detected. These events lasted a few seconds and had many thousands of counts (16500, 5000, 3700, and {gt} 7700. Unfortunately, the association of these gamma ray bursts with thunderstorms or ball lightning was not clearly established, although one of the bursts did occur during a local thunderstorm in rough coincidence with a lightning bolt striking a flagpole about 100 yards from the gamma ray detection crystals. A pulse height spectrum taken for this burst (no spectrum was taken for the other three) exhibited a significant peak, well above background, the energy of which appeared to be compatible with the 511 keV positron annihilation line. While the peak could not be unambiguously attributed to positron annihilation, this certainly appeared to be the most likely source.

  13. A new technique for lag screw placement in the dynamic hip screw fixation of intertrochanteric fractures: decreasing radiation time dramatically

    PubMed Central

    Sheng, Wei-Chao; Li, Jia-Zhen; Chen, Sheng-Hua

    2008-01-01

    The goal of this study was to confirm the decrease in radiation time required for a new technique to place dynamic hip screws (DHS) in intertrochanteric fractures. Seventy-six patients were treated with DHS by either the new technique (NT) or the conventional technique (CT). The width of femoral shaft, the length of the hip screw to be implanted into the injured side, and the distance between the tip of the greater trochanter and the entry point of the guide wire were measured at the uninjured side on the anteroposterior pelvic radiograph preoperatively, and the actual width of the injured femoral shaft was measured intra-operatively. Finally, the entry point and the length of hip screw were obtained through an equation. Mean radiation time of the NT patients (24.57 ± 7.80 s) was significantly shorter than the CT patients (54.2 ± 18.26 s) (P  < 0.001). The new technique decreased radiation time dramatically in DHS fixation. PMID:18265981

  14. Estimation of Evapotranspiration as a function of Photosynthetic Active Radiation

    NASA Astrophysics Data System (ADS)

    Wesley, E.; Migliaccio, K.; Judge, J.

    2012-12-01

    The purpose of this research project is to more accurately measure the water balance and energy movements to properly allocate water resources at the Snapper Creek Site in Miami-Dade County, FL, by quantifying and estimating evapotranspiration (ET). ET is generally estimated using weather based equations, this project focused on estimating ET as a function of Photosynthetic Active Radiation (PAR). The project objectives were first to compose a function of PAR and calculated coefficients that can accurately estimate daily ET values with the least amount of variables used in its estimation equation, and second, to compare the newly identified ET estimation PAR function to TURC estimations, in comparison to our actual Eddy Covariance (EC) ET data and determine the differences in ET values. PAR, volumetric water content (VWC), and temperature (T) data were quality checked and used in developing singular and multiple variable regression models fit with SigmaPlot software. Fifteen different ET estimation equations were evaluated against EC ET and TURC estimated ET using R2 and slope factors. The selected equation that best estimated EC ET was cross validated using a 5 month data set; its daily and monthly ET values and sums were compared against the commonly used TURC equation. Using a multiple variable regression model, an equation with three variables (i.e., VWC, T, and PAR) was identified that best fit EC ET daily data. However, a regression was also found that used only PAR and provided ET predictions of similar accuracy. The PAR based regression model predicted daily EC ET more accurately than the traditional TURC method. Using only PAR to estimate ET reduces the input variables as compared to using the TURC model which requires T and solar radiation. Thus, not only is the PAR approach more accurate but also more cost effective. The PAR-based ET estimation equation derived in this study may be over fit considering only 5 months of data were used to produce the PAR

  15. Radiation, temperature, and vacuum effects on piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Giurgiutiu, Victor; Postolache, Cristian; Tudose, Mihai

    2016-03-01

    The effect of radiation, temperature, and vacuum (RTV) on piezoelectric wafer active sensors (PWASs) is discussed. This study is relevant for extending structural health monitoring (SHM) methods to space vehicle applications that are likely to be subjected to harsh environmental conditions such as extreme temperatures (hot and cold), cosmic radiation, and interplanetary vacuums. This study contains both theoretical and experimental investigations with the use of electromechanical impedance spectroscopy (EMIS). In the theoretical part, analytical models of circular PWAS resonators were used to derive analytical expressions for the temperature sensitivities of EMIS resonance and antiresonance behavior. Closed-form expressions for frequency and peak values at resonance and antiresonance were derived as functions of the coefficients of thermal expansion, {α }1, {α }2, {α }3; the Poisson ratio, ν and its sensitivity, \\partial ν /\\partial T; the relative compliance gradient (\\partial {s}11E/\\partial T)/{s}11E; and the Bessel function root, z and its sensitivity, \\partial z/\\partial T. In the experimental part, tests were conducted to subject the PWAS transducers to RTV conditions. In one set of experiments, several RTV exposure, cycles were applied with EMIS signatures recorded at the beginning and after each of the repeated cycles. In another set of experiments, PWAS transducers were subjected to various temperatures and the EMIS signatures were recorded at each temperature after stabilization. The processing of measured EMIS data from the first set of experiments revealed that the resonance and antiresonance frequencies changed by less than 1% due to RTV exposure, whereas the resonance and antiresonance amplitudes changed by around 15%. After processing an individual set of EMIS data from the second set of experiments, it was determined that the relative temperature sensitivity of the antiresonance frequency ({f}{{AR}}/{f}{{AR}}) is approximately 63.1× {10

  16. Recent radiation effects activities at JPL: Coping with COTS

    NASA Technical Reports Server (NTRS)

    Barnes, C.; Johnston, A.; Lee, C.; Swift, G.; Rax, B.

    1997-01-01

    Radiation effects and testing programs on commercial off-the-shelf (COTS) devices and circuits, which are important for NASA programs, are discussed. Demands for increased performance levels in spacecraft systems is stimulating the use of electronic and photonic devices. Some advances in electronics to reach high performance will result in the miniaturization of devices, which will lead to increased radiation vulnerability.

  17. Total Participation Techniques: Making Every Student an Active Learner

    ERIC Educational Resources Information Center

    Himmele, Persida; Himmele, William

    2011-01-01

    Yes, there are easy-to-use and incredibly effective alternatives to the "stand and deliver" approach to teaching that causes so many students to tune out--or even drop out. Here's your opportunity to explore dozens of ways to engage K-12 students in active learning and allow them to demonstrate the depth of their knowledge and understanding. The…

  18. Application of activation techniques to biological analysis. [813 references

    SciTech Connect

    Bowen, H.J.M.

    1981-12-01

    Applications of activation analysis in the biological sciences are reviewed for the period of 1970 to 1979. The stages and characteristics of activation analysis are described, and its advantages and disadvantages enumerated. Most applications involve activation by thermal neutrons followed by either radiochemical or instrumental determination. Relatively little use has been made of activation by fast neutrons, photons, or charged particles. In vivo analyses are included, but those based on prompt gamma or x-ray emission are not. Major applications include studies of reference materials, and the elemental analysis of plants, marine biota, animal and human tissues, diets, and excreta. Relatively little use of it has been made in biochemistry, microbiology, and entomology, but it has become important in toxicology and environmental science. The elements most often determined are Ag, As, Au, Br, Ca, Cd, Cl, Co, Cr, Cs, Cu, Fe, Hg, I, K, Mn, Mo, Na, Rb, Sb, Sc, Se, and Zn, while few or no determinations of B, Be, Bi, Ga, Gd, Ge, H, In, Ir, Li, Nd, Os, Pd, Pr, Pt, Re, Rh, Ru, Te, Tl, or Y have been made in biological materials.

  19. Neutron spectrum measurements in DT discharges using activation techniques

    NASA Astrophysics Data System (ADS)

    Esposito, B.; Bertalot, L.; Loughlin, M.; Roquemore, A. L.

    1999-01-01

    The JET activation system has eight irradiation ends where samples may be irradiated in the neutron flux from the plasma. There is one end, re-entrant into the top of the vessel, for which there is little intervening material between it and the plasma; the other ends, including two beneath the divertor coils, have increasingly larger amounts of intervening structure. The local neutron spectrum at each irradiation end was measured by simultaneously activating several elemental foils (Al, Au, Co, Fe, In, Mg, Nb, Ni, Ti, Zr). There were 15 activation reactions in the energy range of 0.5-16 MeV which were used as input to the SNL-SAND-II code to determine the neutron energy spectrum. The results are compared with neutron transport calculations both from the MCNP and FURNACE codes: the average standard deviation between measured to SNL-SAND-II calculated activity ratios was as low as 5%. The results demonstrate the reliability of the neutronics calculations and have implications for the design of diagnostics and blankets for the next generation of large tokamaks such as ITER. The 377.9 keV line of the 54Fe(n,2n)53Fe reaction (threshold ˜13.9 MeV, not a dosimetric standard) has also been measured in different plasma conditions. The ratio of the saturated activity from this reaction to that from the 56Fe(n,p)56Mn reaction (threshold ˜4.5 MeV) provides information on the broadening of the 14 MeV fusion peak.

  20. Active Dust Mitigation Technology for Thermal Radiators for Lunar Exploration

    NASA Technical Reports Server (NTRS)

    Calle, C. I.; Buhler, C. R.; Hogue, M. D.; Johansen, M. R.; Hopkins, J. W.; Holloway, N. M. H.; Connell, J. W.; Chen, A.; Irwin, S. A.; Case, S. O.; VanSuetendael, N. J.; Snyder, S. J.; Clements, J. S.

    2010-01-01

    Dust accumulation on thermal radiator surfaces planned for lunar exploration will significantly reduce their efficiency. Evidence from the Apollo missions shows that an insulating layer of dust accumulated on radiator surfaces could not be removed and caused serious thermal control problems. Temperatures measured at different locations in the magnetometer on Apollo 12 were 38 C warmer than expected due to lunar dust accumulation. In this paper, we report on the application of the Electrodynamic Dust Shield (EDS) technology being developed in our NASA laboratory and applied to thermal radiator surfaces. The EDS uses electrostatic and dielectrophoretic forces generated by a grid of electrodes running a 2 micro A electric current to remove dust particles from surfaces. Working prototypes of EDS systems on solar panels and on thermal radiators have been successfully developed and tested at vacuum with clearing efficiencies above 92%. For this work EDS prototypes on flexible and rigid thermal radiators were developed and tested at vacuum.

  1. Risk of whole body radiation exposure and protective measures in fluoroscopically guided interventional techniques: a prospective evaluation

    PubMed Central

    Manchikanti, Laxmaiah; Cash, Kim A; Moss, Tammy L; Rivera, Jose; Pampati, Vidyasagar

    2003-01-01

    Background Fluoroscopic guidance is frequently utilized in interventional pain management. The major purpose of fluoroscopy is correct needle placement to ensure target specificity and accurate delivery of the injectate. Radiation exposure may be associated with risks to physician, patient and personnel. While there have been many studies evaluating the risk of radiation exposure and techniques to reduce this risk in the upper part of the body, the literature is scant in evaluating the risk of radiation exposure in the lower part of the body. Methods Radiation exposure risk to the physician was evaluated in 1156 patients undergoing interventional procedures under fluoroscopy by 3 physicians. Monitoring of scattered radiation exposure in the upper and lower body, inside and outside the lead apron was carried out. Results The average exposure per procedure was 12.0 ± 9.8 seconds, 9.0 ± 0.37 seconds, and 7.5 ± 1.27 seconds in Groups I, II, and III respectively. Scatter radiation exposure ranged from a low of 3.7 ± 0.29 seconds for caudal/interlaminar epidurals to 61.0 ± 9.0 seconds for discography. Inside the apron, over the thyroid collar on the neck, the scatter radiation exposure was 68 mREM in Group I consisting of 201 patients who had a total of 330 procedures with an average of 0.2060 mREM per procedure and 25 mREM in Group II consisting of 446 patients who had a total of 662 procedures with average of 0.0378 mREM per procedure. The scatter radiation exposure was 0 mREM in Group III consisting of 509 patients who had a total 827 procedures. Increased levels of exposures were observed in Groups I and II compared to Group III, and Group I compared to Group II. Groin exposure showed 0 mREM exposure in Groups I and II and 15 mREM in Group III. Scatter radiation exposure for groin outside the apron in Group I was 1260 mREM and per procedure was 3.8182 mREM. In Group II the scatter radiation exposure was 400 mREM and with 0.6042 mREM per procedure. In Group III

  2. Active-contour-based image segmentation using machine learning techniques.

    PubMed

    Etyngier, Patrick; Ségonne, Florent; Keriven, Renaud

    2007-01-01

    We introduce a non-linear shape prior for the deformable model framework that we learn from a set of shape samples using recent manifold learning techniques. We model a category of shapes as a finite dimensional manifold which we approximate using Diffusion maps. Our method computes a Delaunay triangulation of the reduced space, considered as Euclidean, and uses the resulting space partition to identify the closest neighbors of any given shape based on its Nyström extension. We derive a non-linear shape prior term designed to attract a shape towards the shape prior manifold at given constant embedding. Results on shapes of ventricle nuclei demonstrate the potential of our method for segmentation tasks. PMID:18051143

  3. Techniques for active embodiment of participants in virtual environments

    SciTech Connect

    Hightower, R.; Stansfield, S.

    1996-03-01

    This paper presents preliminary work in the development of an avatar driver. An avatar is the graphical embodiment of a user in a virtual world. In applications such as small team, close quarters training and mission planning and rehearsal, it is important that the user`s avatar reproduce his or her motions naturally and with high fidelity. This paper presents a set of special purpose algorithms for driving the motion of the avatar with minimal information about the posture and position of the user. These algorithms utilize information about natural human motion and posture to produce solutions quickly and accurately without the need for complex general-purpose kinematics algorithms. Several examples illustrating the successful applications of these techniques are included.

  4. Photosynthetically active radiation (PAR) x ultraviolet radiation (UV) interact to initiate solar injury in apple

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sunburn or solar injury (SI) in apple is associated with high temperature, high visible light and ultraviolet radiation (UV). Fruit surface temperature (FST) thresholds for SI related disorders have been developed but there are no thresholds established for solar radiation. The objectives of the s...

  5. Successful Application of Active Learning Techniques to Introductory Microbiology

    PubMed Central

    HOFFMAN, ELIZABETH A.

    2001-01-01

    While the traditional lecture format may be a successful way to teach microbiology to both medical and nursing students, it was not an effective means of learning for many prenursing and preprofessional students enrolled in either of the introductory microbiology courses at Ashland Community College, an open enrollment institution. The structure of both Medical Microbiology and Principles of Microbiology was redesigned to allow students to address the material in an active manner. Daily quizzes, student group discussions, scrapbooks, lab project presentations and papers, and extra credit projects were all added in order to allow students maximum exposure to the course material in a manner compatible with various methods of learning. Student knowledge, course evaluations, and student success rates have all improved with the active learning format. PMID:23653538

  6. Aerial monitoring in active mud volcano by UAV technique

    NASA Astrophysics Data System (ADS)

    Pisciotta, Antonino; Capasso, Giorgio; Madonia, Paolo

    2016-04-01

    UAV photogrammetry opens various new applications in the close range domain, combining aerial and terrestrial photogrammetry, but also introduces low-cost alternatives to the classical manned aerial photogrammetry. Between 2014 and 2015 tree aerial surveys have been carried out. Using a quadrotor drone, equipped with a compact camera, it was possible to generate high resolution elevation models and orthoimages of The "Salinelle", an active mud volcanoes area, located in territory of Paternò (South Italy). The main risks are related to the damages produced by paroxysmal events. Mud volcanoes show different cyclic phases of activity, including catastrophic events and periods of relative quiescence characterized by moderate activity. Ejected materials often are a mud slurry of fine solids suspended in liquids which may include water and hydrocarbon fluids, the bulk of released gases are carbon dioxide, with some methane and nitrogen, usually pond-shaped of variable dimension (from centimeters to meters in diameter). The scope of the presented work is the performance evaluation of a UAV system that was built to rapidly and autonomously acquire mobile three-dimensional (3D) mapping data in a volcanic monitoring scenario.

  7. Figure Analysis: A Teaching Technique to Promote Visual Literacy and Active Learning

    ERIC Educational Resources Information Center

    Wiles, Amy M.

    2016-01-01

    Learning often improves when active learning techniques are used in place of traditional lectures. For many of these techniques, however, students are expected to apply concepts that they have already grasped. A challenge, therefore, is how to incorporate active learning into the classroom of courses with heavy content, such as molecular-based…

  8. The Effectiveness of Active and Traditional Teaching Techniques in the Orthopedic Assessment Laboratory

    ERIC Educational Resources Information Center

    Nottingham, Sara; Verscheure, Susan

    2010-01-01

    Active learning is a teaching methodology with a focus on student-centered learning that engages students in the educational process. This study implemented active learning techniques in an orthopedic assessment laboratory, and the effects of these teaching techniques. Mean scores from written exams, practical exams, and final course evaluations…

  9. High Energy Radiation Induced Activation of COX-2 and MMP-9 is Mediated by NF-kappaB

    NASA Astrophysics Data System (ADS)

    Rolle, G.; Munyu, S.; Jejelowo, O. A.; Sodipe, A.; Shishodia, S.

    2010-04-01

    Space radiation is a known carcinogen, and astronauts are exposed to high-energy radiation. In this study, we demonstrate that high-energy radiation activates cylooxygenase-2 and matrix metalloproteinase-9 through the NF-kB pathway.

  10. Naturally induced secondary radiation in interplanetary space: Preliminary analyses for gamma radiation and radioisotope production from thermal neutron activation

    NASA Astrophysics Data System (ADS)

    Plaza-Rosado, Heriberto

    1991-09-01

    Thermal neutron activation analyses were carried out for various space systems components to determine gamma radiation dose rates and food radiation contamination levels. The space systems components selected were those for which previous radiation studies existed. These include manned space vehicle radiation shielding, liquid hydrogen propellant tanks for a Mars mission, and a food supply used as space vehicle radiation shielding. The computational method used is based on the fast neutron distribution generated by the BRYNTRN and HZETRN transport codes for Galactic Cosmic Rays (GCR) at solar minimum conditions and intense solar flares in space systems components. The gamma dose rates for soft tissue are calculated for water and aluminum space vehicle slab shields considering volumetric source self-attenuation and exponential buildup factors. In the case of the lunar habitat with regolith shielding, a completely exposed spherical habitat was assumed for mathematical convenience and conservative calculations. Activation analysis of the food supply used as radiation shielding is presented for four selected nutrients: potassium, calcium, sodium, and phosphorus. Radioactive isotopes that could represent a health hazard if ingested are identified and their concentrations are identified. For nutrients soluble in water, it was found that all induced radioactivity was below the accepted maximum permissible concentrations.